Haruno Shiobana was the son of DIO (fathered using Jonathan Joestar´s body) and a Japanese woman. His first years were marked by his mother's neglect, as she left home often due to his existence threatening her party life, forcing Haruno to be left alone at night to fear the dark, too scared to even cry. When he turned four, his mother married an Italian man and they moved to Italy, resulting in Haruno changing his name to "Giorno Giovanna". His new stepfather, however, would often beat him for always trying to read others when his mother was not around, even though it was that same physical abuse that brought about Giorno's habit. That, coupled with the fact that Giorno easily became the target of bullies, gave him very low self-esteem, to the point of believing himself to be scum and setting him on the path to becoming twisted and immoral.
However, one day as Giorno was walking home, he came upon a man covered in blood lying in a patch of tall grass. After discovering the injured man, other men approached Giorno, asking him if he knew where the man had gone. Giorno lied to the men, feeling that the injured man was the same as him, and subconsciously activated his Stand's ability to mask the man's presence by causing the grass to grow taller and bloom flora. Around two months later, the man showed himself to Giorno again and told him that he would never forget what had been done for him. Things soon turned brighter for Giorno: his father stopped beating him and he became popular among kids his own age. It turned out that the man was a gangster who quietly watched over Giorno from the shadows. To Giorno, this was the first time someone else had treated him like a human being and showed him respect. The trust that Giorno should have learned from his father was instead taught to him by others, and ever since then something that can be described as a "cool breeze" blew inside his heart, marking his change from a cold and antisocial individual to a charming and righteous one. He subsequently forges a dream to make the corrupt Italian mafia like the man who had helped him, and strive to become a "Gang-Star".
In March 29, 2001, Giorno is 15 years old and operates as a petty thief at the Naples airport. Koichi Hirose meets Giorno showing off his famous trick in which he stuffs his entire ear into his ear canal. Giorno offers Koichi a ride as an illegal taxi, but in fact steals his luggage and drives away. Koichi uses Echoes' 3 Freeze to increase the weight of the tires. Giorno gives Koichi a sly smile and runs away, after using his Stand's power to turn Koichi's luggage into a frog.
Giorno then has an encounter with Leaky-eye Luca, who demands protection money from him. Giorno claims to not have any, but Luca, who is unconvinced, takes Giorno's wallet and reveals a picture of DIO. Luca becomes increasingly violent while Giorno insists that he has no money. Suddenly the frog mutated from Koichi's luggage returns and begins climbing up Giorno's pants. Upon seeing the frog, Luca orders him to kill it, but Giorno refuses, claiming it to not anything to do with their situation. The refusal enrages Luca, who attempts smash both the frog and Giorno with his shovel against Giorno's suggestions, but the side effects of his Stand ability manifest and cause the attack to rebound upon and send him into a coma from severe head trauma.
Giorno then spends the money stolen from Koichi, but the two meet again. Koichi makes the first move and uses 3 Freeze on Giorno's hand, forcing him to finally reveal his Stand, Gold Experience, and escape a second time. Soon, problems arise for Giorno as news of Luca's death spreads, and Bruno Bucciarati visits him on the funicular to interrogate him. Bucciarati's interrogation eventually turns violent, forcing Giorno to openly fight. Giorno uses Gold Experience's live-giving ability offensively for the first time, resulting in him gaining the upper hand. This forces Bucciarati to try and flee, making Giorno give chase as the gangster's escape would mark Giorno an assassination target. Finally catching Bucciarati, they meet fists once more, with Giorno injuring his own arm to allow a decisive punch to his opponent. However, he doesn't deal the finishing blow as he senses that Bucciarati is a good man, figured out when he temporarily shows disappointment at the drug-injected arm of a young teenager during the fight. Giorno correctly acknowledges that the gangster won't attack him anymore, something Bucciarati indeed follows through with, and both develop a mutual respect. Giorno boldly reveals his dream to become a "Gang-Star" who will take over the Neapolitan mafia in order to defend the innocent, and Bucciarati agrees to help him infiltrate the most powerful gang in Naples, Passione.
Giorno meets a lieutenant, or "capo", of Passione known as Polpo in prison, who gives him a lighter and tells him to keep it lit for 24 hours in order to join the gang. Giorno manages to sneak the lighter out of prison, go to his student room, and avoid a snooping Koichi while keeping his lighter lit, but a janitor accidentally splashes the lighter and extinguishes it. As Giorno tries to figure out what to do, the janitor relights the lighter for him and Polpo's Stand Black Sabbath appears. It attacks the janitor for having re-lit the lighter, ultimately killing him by stabbing his spirit with the Arrow. The Stand then turns its attention to Giorno, who fights back with Gold Experience but is overpowered. Giorno figures out its weakness to sunlight, and proceeds to take various measures and strategies to bring the Stand out into the sun, before Koichi once again becomes involved. Thanks to Koichi's help and counsel, Giorno manages to destroy Black Sabbath, nearly having his own ankles broken in the process. The next day, Giorno meets Polpo again, who accepts him within Passione, hoping to use Giorno as another tool. However, in retaliation for Polpo killing the janitor and "insulting his life", Giorno transforms a gun into a banana, leading to Polpo killing himself when he tries to eat it.
Giorno then becomes the newest member of Bucciarati's Gang of five. When brought to meet the rest of the members, he is pressured into drinking a cup of "tea" heavily mixed with Leone Abbacchio's urine. He earns their acceptance and awe by doing so without hesitation, having turned his teeth into jellyfish made of 98% water which absorbed all of the water molecules.
After Polpo's death, the seat of Passione lieutenant becomes available. Bucciarati takes the group on a boat to Capri Island to retrieve Polpo's hidden fortune of 6 billion yen in order to court the Passione higher-ups and get Polpo's position. During the trip, the group faces Mario Zucchero, another Passione member looking for the treasure, and his mysterious Stand. Although Giorno's teammates are disappearing one by one, Giorno manages to deduce that everyone is alive. Before the distrustful Abbacchio, Giorno allows himself to be attacked and captured by the enemy Stand in order to help him reveal its ability. A fly transformed from Narancia Ghirga's shoe by Gold Experience enables Abbacchio and Bucciarati to track the captured members and figure out the secret behind the enemy Stand and defeat it and its user.
Upon discovering that their rival gangster has a partner who ran ahead to Capri Island, Giorno and another member of the gang, Guido Mista, go ahead of the rest on an inner-tube-turned-fish to clear the way, in which Giorno keeps track of Mista's movements and Mista encounters Sale. After Sale's defeat by Mista, the group encounter another capo named Pericolo, who has come at Bucciarati's request to take the money and subsequently raise Bucciarati to lieutenant rank. They then receive their first mission: to protect Trish Una, the daughter of Passione's boss, from the traitors seeking to capture her in hope of getting information on the Boss and using her as leverage against him.
Giorno's group must now bodyguard Trish Una until the traitors are killed. However, not one day after, Narancia is discovered by Formaggio, a member of the traitorous assassination squad La Squadra di Esecuzione. While Narancia manages to kill Formaggio, the group's hideout is practically discovered. Giorno correctly predicts that the Boss would issue new orders immediately.
Bucciarati's Gang is told via computer that they have to retrieve a key in Pompeii in order to secure an unknown mode of transportation that is safe. In Pompeii, Giorno, Abbacchio, and Pannacotta Fugo fight Illuso, also an assassin. Abbacchio and Fugo are subsequently imprisoned in the mirror world created by Illuso's Man in the Mirror. Giorno retrieves the key with Abbacchio's help, though instead of abandoning his comrades and escaping, he infects himself with the killer virus of Fugo's Stand Purple Haze, and lets himself get attacked by Illuso in order to spread it to him. Giorno creates a snake that tracks Illuso's movements and location, allowing Fugo to properly corner the enemy with Purple Haze and kill him without needing to see him. Despite Fugo's insistence that Purple Haze's virus will inevitably kill him, Giorno saves himself by creating antibodies with Gold Experience's power. Fugo is left astonished by how Giorno's actions always lead to success, and openly salutes him.
On the key are engraved the Boss' next orders: Bucciarati must now to go to the Naples train station then hitch a train ride to Venice. While the gang meets the turtle Coco Jumbo which can act as a shelter and hiding spot for everyone due to its Stand Mr.President, they are pursued by an assassin duo.
Inside the train, Bucciarati's Gang is attacked by the team Pesci and Prosciutto, and suddenly everyone grows old. Before succumbing to the forced aging, Giorno still manages to work out how Prosciutto's The Grateful Dead functions and its weaknesses, and relays it to the rest of his team. Mista and Bucciarati would use that knowledge to defeat both Prosciutto and Pesci. However during the battle, Pesci stops the train after killing the drivers, and the gang is now immobilized.
Still having to go to Venice, Bucciarati's Gang first try to hitch a ride, but the misbehavior of Mista's Stand Sex Pistols force him to knock out the driver, leaving the gang to have to change their plan again.
In a parking lot, Giorno impresses everyone a second time by using his power to change a large number of cars into masses of frogs and give the illusion that many cars were stolen so that the car the gang actually takes will be harder to track.Meanwhile another assassin, Melone, used his Stand Baby Face to track Bucciarati and neutralize both him and Trish inside the turtle. The autonomous Stand, blocked by Giorno, is ordered to kill him. At first, Baby Face seemingly kills Giorno by stealing a piece of his eye and throat and leaving him to die. However, it is then that Giorno, inches from death, is finally able to learn of Gold Experience's capacity to mend injuries by converting objects into the needed flesh and bones, using it to save himself. This newfound ability gives him the upper hand against Baby Face, and he attacks the Stand before it can escape with the turtle. Baby Face disguises itself as Giorno's shadow and ambushes him, but Giorno turns a hand of his that was previously cut off by the enemy's ability into a piranha, which eats its way through Baby Face. Baby Face retaliates by attacking Giorno's reattached hand once more. However, the hand was never meant to stay attached, as Giorno created it out of the entirety of Melone's motorcycle for the sole purpose of letting Baby Face attack it. Giorno is able win against it without the help of the others by trapping the Stand inside of the motorcycle and blowing it up. Afterward, Giorno sends a lethally venomous snake made out of Baby Face's corpse to Melone, who is bitten.
Bucciarati receives new orders from the Boss, who tells him to retrieve an unknown item in Venice. Giorno and Mista are assigned to retrieve it by car while the rest of the group will enter Venice by boat. However, the assassin Ghiaccio attacks both of them and a race toward the item begins. Unfortunately, Ghiaccio's ice Stand White Album is practically immune to Gold Experience and Sex Pistols, preventing the creation of life with its cold and using ice armor to stop bullets, respectively. Making the mistake of underestimating Ghiaccio, Giorno is imprisoned by ice while their car is sinking in the sea, and despairs to survive this encounter. Yet, Giorno creates grass out of various car parts to allow Mista to escape, as he discovered a weak point in Ghiaccio's armor. In the ensuing shootout, Mista is still overpowered by Ghiaccio, and Giorno notices that Mista has resolved to give his own life for the sake of the mission; a "will of self-sacrifice" that goes against Giorno's idea of what resolve is. He calls out to him, telling him that resolve is to "carve out one's destined path through the darkness", before grievously damaging his own arm and flinging the blood at Ghiaccio, creating floating crystals that allow Mista to see his target clearly. Mista thanks Giorno for his ever-present guidance before having one last bout with Ghiaccio and sending his neck onto a splintered lamppost. Although Ghiaccio continues to live, him undoing his ability unintentionally sets Giorno free. Giorno saves Mista when he is shot in the head and heals him while praising his resolve, then finishes Ghiaccio off by having Gold Experience rapidly kick him until his neck is completely impaled. In the aftermath, Mista admits how grateful he is to Giorno and his actions, though Giorno merely points out how painful his Stand's healing process will be.
The two retrieve a disk which contains the Boss's last orders and are ordered to bring Trish to the San Giorgio Maggiore basilisk. Giorno, opportunistic to find the Boss' identity, gives Bucciarati a living brooch in order to track the Boss. Unexpectedly, the Boss actually wanted to kill Trish, and Bucciarati openly revolts and fights the Boss. Alas, Bucciarati is no match for the Boss' Stand King Crimson. Giorno notices that something is wrong when time seems to skip and rapidly intervenes the moment Bucciarati's phone is destroyed, using Gold Experience's ability to stall the Boss long enough to save Trish and allow Bucciarati the chance to escape. Bucciarati apparently succumbs to his injuries when Giorno reaches him, resulting in him trying to shake Bucciarati awake after mending his injuries. Shortly after, Giorno hears Bucciarati's voice call out to him from behind before Bucciarati wakes up. The two announce to the rest of the group that they openly rebelled against the Boss, and though most are scared, everyone but Fugo follows Bucciarati. Giorno notices that Bucciarati does not react to pain, does not bleed, and that he is abnormally cold to the touch.
Still in Venice, Bucciarati's Gang debate what to do. Trish eventually informs them that the Boss met her mother in the island of Sardegna, giving the group a solid lead. At the same time, Passione operatives Tiziano and Squalo stealthily attack the group. Narancia is forced to constantly lie because of Tiziano's Talking Head, but Giorno soon becomes the first and only one to suspect that they are under attack. While the shark-like Clash nearly kills him, Giorno manages to counsel Narancia to go after the Stand users, taking bullets from his Aerosmith in order to help Narancia keep track of his location and giving him a spare tongue to nullify the effects of Talking Head. Narancia manages to kill both by tricking them with the spare tongue into believing that he was lying about finding them. Narancia mentally praises Giorno, and believes him to be the reason why the gang might win against the Boss.
With the defeat of Squalo and Tiziano, the group decides to use the chance they have and leave Venice by plane. However, while attempting to steal a jet from a nearby army airport, they are confronted by a mysterious man. Mista ends up killing the man with ease after several warnings to back away, but Giorno is left suspicious.
In the plane, Giorno's suspicions are confirmed when the Stand Notorious B.I.G attacks the group. The Stand proves invulnerable, severely wounding both Narancia and Mista by consuminng much of their Stands and forcing Giorno to sacrifice both of his hands trying to remove Notorious B.I.G from the plane. The gang retreats to the pilot's cabin and without his hands, Giorno can no longer heal anyone, including himself. Trish discovers one of his brooches slowly turning into a hand; an action done by Giorno in preparation for the loss of both his hands. Unfortunately Notorious B.I.G catches up to the plane, but Trish awakens her Stand Spice Girl when she becomes determined to make sure that the replacement hand stays safe. Ultimately Trish manages to bring Giorno his hand and destroys the plane, plunging Notorious B.I.G into the sea.
In Sardegna, Bucciarati's Gang investigate the Boss' past. Abbacchio uses his Moody Blues to rewind events to when the Boss met Trish's mother, while the rest of the group are attracted by strange happenings occurring a bit away (the Boss' subordinate Vinegar Doppio in a battle with la Squadra's leader Risotto Nero). They find a boy with his mouth stitched shut and clothes stolen, and Bucciarati realizes too late that they left Abbacchio vulnerable, where he is killed by the Boss. Narancia desperately begs Giorno to heal him, though Giorno grievously remarks that Abbacchio's death was too sudden for him to be saved. Despite Bucciarati ordering the group away from the body, Giorno discovers that Abbacchio rewinded far enough in time to expose a negative of the Boss's face and fingerprints. While their attempts to investigate the police databases with the mold is fruitless, Bucciarati's Gang are noticed by a third party who reveals the Boss' name, Diavolo and his Stand, King Crimson's ability to erase time. Showing them the Arrow to gain their trust, the unknown individual promises them a power able to defeat King Crimson when they meet in Rome. While they depart, the Boss sees their determination and suspects that he hasn't won yet, then pursues them to Rome.
Upon arriving to the coasts of Italy, the group is attacked by another Stand which causes explosive mold growth. Moreover, another Stand user able to swim through solid concrete attacks them as well. The duo Cioccolata and Secco tries to kill Bucciarati's Gang on the coast but Giorno, managing to deduce how Cioccolata's power functions, enables the whole group to steal a car and try to escape from their enemy. On the way, Bucciarati reveals that he's been dead since the first encounter with Diavolo, that he was only able to continue when Gold Experience gave his body life, and that his time was running out as his senses began to dull and his body deteriorate.Cioccolata and Secco follow them to Rome where Cioccolata's Green Day causes chaos as he flies around in a helicopter. Mista is initially unable to hit the helicopter, but Giorno assists him and makes the next round of bullets turn into branching vines that ensnare the helicopter. Giorno and Mista split from Bucciarati to fight Cioccolata, getting to the roof of the building the heli was caught. Sex Pistols, and by extension Mista himself, are incapacitated with the exception of No.5 when fired into the helicopter, and Giorno decides to approach Cioccolata alone, seeing the widespread death and chaos caused by the mad doctor. After a scuffle with Cioccolata's dismembered body, Giorno is sent falling off the building, only to use the bullet brought by No.5 to catch himself with a branch he created. Cioccolata is shot in the head by said bullet when he tries to make Giorno fall once more, and is seemingly killed. Giorno begins speaking to his body that he will spare him if he does not move when he approaches him, and the doctor reveals himself alive and attempts to kill Mista. A beetle begins eating the doctor's brain as Giorno reveals that he was buying time for the bullet to transform, and that he lied to Cioccolata about sparing him in order for him to let his guard down. Gold Experience finishes Cioccolata off with a lengthy barrage of punches, sending the various body parts into a trash compactor as Giorno attends to Mista.
Bucciarati also manages to kill Secco, but as the group was split, Vinegar Doppio is able to approach their contact first. Jean Pierre Polnareff, who had been working against Diavolo for many years, confronts the Boss. Giorno realizes that time is skipping and warns Mista and Trish. Polnareff is fatally injured, left with no choice but to use the Arrow on his Silver Chariot. Chariot Requiem awakens out of Silver Chariot and makes everyone in Rome fall asleep and switches their souls. Great confusion arises as Giorno finds himself in Narancia's body, and Diavolo is now inhabited by Bucciarati's soul. Bucciarati orders Mista to disable whomever's in his unconscious body, which he follows through with, unwittingly killing Doppio as a result. However, Narancia is brutally impaled on broken iron bars momentarily afterward, and everyone notices that time has been erased. Giorno is the first to realize that Diavolo and King Crimson were not the ones in Bucciarati's body. Pushing everyone out of the way to get to Narancia, Giorno realizes that he died instantly, and that all he can do is return to his own body. Before returning to the problem of Chariot Requiem, Giorno mourns Narancia's death and covers his body with flora. Promising Narancia that he won't let anybody hurt him anymore, and to take him home, Giorno becomes more determined than ever to seize the Arrow and bring Diavolo down.
The group moves towards Requiem, and finds out that it is oblivious to those that do not attempt to take the Arrow from it. Bucciarati trips it, causing it to drop the Arrow. Giorno reaches for it, only for Gold Experience's hand to press against his as it peers out of a crack in the ground. He then tosses a rock at the Arrow, and is nearly hit by the rock in the back of his head. It is then Giorno is convinced that Requiem will not allow anything to come in contact with the Arrow. However, this does not prove true for Polnareff, whom no longer has control of his own Stand. Upon taking the Arrow in his mouth, Requiem gets up and attacks him, even after he drops it. When Mista attempts to shoot Requiem and slow it down, his gun breaks, seemingly from metal fatigue, and he switches it out with a pistol from a nearby police officer. This catches Giorno's eye as he begins to sense something else at work. Requiem, just as quickly as it began to attack Polnareff, ceases, takes the Arrow, and begins walking away once more. This leaves the group in confusion, but Polnareff tells everyone that they are slowly turning into something unknown; Requiem's true ability has just begun.
Before the group continues after Chariot Requiem, Giorno orders everyone to stop. Pulling out Mista's broken revolver, he analyzes it and sees that it was not metal fatigue that caused it to break: it was actively broken by something strong enough to bend and twist metal. He figures out that Diavolo is not only close by, he is possessing one of them and hiding within their bodies in order to sabotage them. Giorno reminds everyone of his ability to sense the amount of life energy in something, claiming it would be able to tell if there is an extra soul in one of their bodies, but King Crimson's notoriously lethal strength would risk someone getting killed in an instant if Giorno entered its range of five meters. Nonetheless, Giorno proceeds to approach his teammates. He tries to start with Mista in Trish's body, but Mista is too paranoid to let Giorno, whom could be possessed himself, to get near him, threatening to shoot. Deciding that it would waste time trying to convince Mista otherwise, Giorno moves onto Bucciarati in Diavolo's body. Before moving, Giorno bites his own index finger and holds it over his hand to let the blood drip; an ability he learned from Polnareff to check to see when time has been erased. When he approaches, him and Bucciarati instantly figure out the time has been erased when the amount of blood drops suddenly increases. King Crimson lashes out at Giorno from behind, severing his arm and punching him in the head. Diavolo takes complete possession of Trish in Mista's body, and sprints for Requiem, dodging all of Mista's attacks with his time erasure. He figures out Requiem's weakness and nearly destroys it, taking the Arrow for himself. However, Giorno made sure to splatter his blood on King Crimson when he was attacked, and transforms the drops into a swarm of ants that chew at and break off the Arrow to take to their creator.
This forces a scuffle between Diavolo and Mista with a weakened Trish, using their Stands to try to take the Arrow. Furious at her very existence, Diavolo kills his hostage Trish in the moment and makes a desperate leap towards the Arrow by flinging Mista's body at it. In a last ditch effort, Bucciarati destroys the remains of Chariot Requiem to return everyone to their bodies, both saving Trish and ripping Diavolo's soul and King Crimson away from the Arrow, at the cost of his own life. Bucciarati thanks Giorno for "bringing him back to life", not just literally, but by restoring the faith in his heart during their first meeting, and ascends to Heaven guided by angels. When the dust settles, the Arrow has landed in Giorno's hands. Taking it for himself with newfound resolve, he pierces Gold Experience with it. Diavolo, freshly returned to his own body, realizes what is happening and does not waste any time moving in to kill Giorno, punching Gold Experience with enough strength to shatter its head. However, a new Stand peers from underneath, and a second attack by King Crimson frees it.
Giorno stands boldly with his very own Requiem Stand: Gold Experience Requiem. Diavolo confidently erases time and moves in to finish Giorno off after a brief demonstration of Gold Experience Requiem's stronger life-giving ability. However, Requiem reveals its true ability to return anything to zero, effectively nullifying any action or process it desires, including King Crimson's time erasure. After Gold Experience Requiem finally destroys King Crimson and pummels Diavolo into the nearby waters, Mista and Trish express an urgent need to find Diavolo. Giorno, however, remains confident that Diavolo is finished, having felt the reassurance of Requiem's power without fully understanding it. Swearing to protect the Arrow that his friends gave their lives for, Giorno eventually take the lead of Passione as a group of dignified men stand before him.
(The information below derives from a Light Novel not written by Araki. As such, it may or may not be considered canon.)
After defeating Diavolo, Giorno reveals himself as the Boss, claiming that he doesn't want traitors to endanger the boss' daughter in an attempt to find his identity. Attracting the attention of the Speedwagon Foundation, Giorno accepts to cooperate with them and, as a gesture of good will, agrees to destroy a Stone Mask. At the same time, Giorno enlists Fugo to help kill Passione's narcotic team alongside operatives Sheila E and Cannolo Murolo. The three manage to fulfill all their objectives.
Giorno meets with Fugo shortly after the latter's defeat of Massimo Volpe, healing his injuries with Gold Experience. Giorno talks to Fugo about the personal progress which he had made and his reasons for sending Fugo off to stop the narcotics team. Fugo deems himself unworthy of Giorno's respect, believing that Bucciarati should be in his place. However, Giorno comforts his crying friend, telling him that he will take on his sorrow. This action leads to Fugo finally accepting Giorno's honor, referring to him as "GioGio".