Josuke is a savvy, confident and courageous teenager. Friendly and loyal, his amiable personality helps him make friends throughout the story.
Josuke's primary trait is his overall kindness, reflected in his Stand Crazy Diamond which repairs and heals. When a random bystander helped saving him out of genuine kindness, Josuke subconsciously reflected that kindness in him. Even upon the revelation that he's Joseph's bastard son, Josuke has thought first and foremost about the troubles he's caused to the Joestars and disregarded any claim for a heritage, only wanting to reassure his biological father that he was doing fine. Agreeable by nature, Josuke isn't as prone to violence as other JoJos and can even calmly tolerate bullying by upperclassmen or Shigechi's selfishness. Josuke is loyal to his friends and loved ones; risking his life after Koichi is hit by Keicho's Bow, and carrying Okuyasu's body while apparently dead throughout the first part of his battle with Yoshikage Kira and Killer Queen. When his grandfather died, Josuke took upon himself to become the protector of Morioh. Upon meeting someone in not particularly antagonistic circumstances, Josuke will generally be polite and friendly.
Overall, Josuke behaves like a teenager, and aside from his general goal of protecting Morioh from any Stand menace, is concerned by more down to earth matters, such as hanging out with his friends. Josuke passively protects his town, and only acts when directly asked by the much more proactive Jotaro or when he directly encounters a Stand user. Curious, Josuke is quick to investigate any unusual phenomenon, which often leads him into a Stand User. Josuke is very prone to openly communicate his feelings, either expressing amazement, amusement, fear and anger thus he appears as a goofy individual.
Sufficiently humble, Josuke confesses to being nervous around famous people, opting not to go with Koichi to first meet Rohan Kishibe due to his great fame as a mangaka. Josuke also has a fear of turtles, and has tried to touch a turtle to get rid of that fear. Josuke isn't shy to admit his limits, and has confessed that he doesn't know much about manga, or isn't good at videogames, even though he isn't happy to have someone know these factoids. In the same way, Josuke tries to live up to Jotaro, whom he admires, and has been nervous around him for fear of not living up to the task Jotaro entrusted to him. He has also shown a mild fear of ghosts (in the beginning), as shown when Koichi wonders if he saw a ghost in the house next to Josuke's, and Josuke nervously tells him to cut it out.
However, in a fight, Josuke is much more calm, and has unshakable confidence in Crazy Diamond, but his confidence doesn't extend to himself, as Josuke can still be nervous if things don't go his way. Additionally, Terunosuke Miyamoto is able to reveal that in terms of body language, Josuke's first unconscious reaction when unsure is to bite his lip. In general, his attitude will mix calmness and goofiness, and Josuke can switch between a taunting one-liner and a serene assertion of the situation. Josuke is occasionally distracted in a fight, often reflecting on the silliness of the situation he's currently in or trying to act cool. Even if Josuke is gentle by nature, he has no qualm about violently pummeling an enemy, and in the case someone has hurt or endangered a family member, Josuke will be even more vindictive, as he fused Angelo with a rock and Terunosuke with a book.
Josuke has a tangential respect of the law at best, having inherited his father's mischevious side, shown primarily in regards to winning money. After nearly emptying his bank account on frivolous spendings, Josuke has been trying to get extra money in quick fashion. When he and Okuyasu meet Shigechi, he quickly devises a plan to exploit Shigechi's Stand Harvest to find first discarded change, and then discarded coupons from all over Morioh, going as far as commit felony to earn the money in a winning ticket. Similarly, after meeting Mikitaka Hazekura, he takes advantage of his shape-shifting Stand power, convincing him to turn into dice in order to cheat money from Rohan, with whom he has a bad relationship. Lastly, characterized as a knowing gesture, he steals Joseph's wallet with his Stand by restoring it to his possession with a piece of a picture planted there. The fact that his Stand can nearly repair or heal anything means that Josuke can get away with destruction of property or endangering someone, thus isn't really concerned about the legal ramifications of his actions since they will be without consequence, at least for him.
When it comes to women, he is moderate between Joseph and Jotaro. He does not flirt relentlessly and is not perverted like Joseph, but when the girls near him express interest in him, he is flattered and has shown to get along quite well with his female classmates and admirers. He does not shoo them away like Jotaro but doesn't relentlessly flirt or pursue any. When Jotaro asks Josuke to go hunting, Josuke initially believes he means hunting for girls and says with a blush and smile that he is more of a love kind of guy. However, he seems to be willing to hit them if they are the enemy as he threatened to kill Yukako if she tried to harm Koichi in anyway (as she is obsessed with Koichi and at one point kidnapped him). While he does express interest in women, it is not his main priority.
As a catchphrase, Josuke often says "Great" in English. He also displays an odd quirk whenever he pronounces the Japanese phrase kakkoii (かっこいい?), a masculine compliment essentially meaning "cool", where he will always pronounce it weirdly like "Kappyoii" or "Kacchoii." This is translated as turning "cool" into "kewl" in the English Crunchyroll subtitles.In a quintessential idiosyncrasy, Josuke takes a hyper-sensitive reaction to comments at all disparaging of his hairstyle; which Josuke explains as due to the honor of a man with the same hairstyle who saved his life as child. After an insult, Josuke enters a blind rage and becomes much more rude and violent. Firstly, a swaggering upperclassman to whom Josuke initially defers is punched and stepped on, before his nose is restored by Crazy Diamond improperly, indefinitely, due to Josuke's mood. Later, during his fight with Rohan, in an attempt to manipulate Josuke into gazing upon his Stand by openly taunting him about his hair, Josuke goes berserk; landing Rohan in hospital for one month.
Friends, Classmates and Others
- Koichi Hirose: Josuke is close friends with Koichi and frequently looks out for his well-being. When Koichi becomes victim to Yukako's intense affection toward him, Josuke takes measures to make Koichi seem less attractive. Josuke respects Koichi's bravery in dire times and sees him as a good friend and worthy ally, trusting him for help throughout various battles.
- Okuyasu Nijimura: Initially, Josuke and Okuyasu met as enemies, but after hearing out Okuyasu's story and motives, Josuke becomes best friends with him. The two frequently hang out with each other and experience day-to-day misadventures. They often encounter or fight Stand users together such as Tonio, Akira, Shigechi, Mikitaka, Toyohiro, and Kira. They have such a strong bond that when Okuyasu was attacked and nearly killed by Kira, Josuke refused to leave him even though it seemed Okuyasu was dead and dragging his body slowed Josuke down.
- Rohan Kishibe: Josuke and Rohan initially met as enemies due to Rohan nearly killing Koichi and Okuyasu. Josuke then gets his hair insulted by Rohan and pummels him in blinded rage. Although their views of each other cool down after that, they do not view each other any more amicably. Rohan becomes suspicious of Josuke's attempts to cheat money from him and Josuke becomes suspicious of Rohan's attempts at revenge. Despite this, the two hold some begrudging respect and trust in each other. Due to their contrasting personalities, Rohan had difficulty getting Josuke to listen to him during the fight with Highway Star and saved Josuke's life while risking his own. Josuke started to respect Rohan after that and risked his life in return by looking for Yuya Fungami in hopes of rescuing Rohan. Although Josuke has healed Rohan's pinky during their game of Cee-lo, and then healed him again after Highway Star, Rohan gets angry afterwards because he never asked Josuke to do so.
- Mikitaka Hazekura: Josuke and Mikitaka see each other as close friends. Mikitaka is especially thankful of Josuke for "saving his life" by finding him in a crop circle and getting him away from loud sirens later on. Josuke does not hesitate to have Mikitaka use his ability to attempt to scam money from Rohan, but becomes worried when Mikitaka displays signs of sickness and attempts to look out for his friend's well-being. In addition, Josuke is moved when Mikitaka offers to sacrifice his freedom to save Josuke from Super Fly during their fight against Toyohiro, and does everything in his power to save him. Overall, the two are good loyal friends who stand by each other.
- Josuke's Savior: In a past incident in which Josuke had a fever and the car his mom drove was stuck in a snowstorm, an unnamed student with a pompadour took off his coat and placed it underneath the car. By doing so, the car was able to start up and drive over the coat safely as the student pushed the car from behind. This caused Josuke to look up to the student as a role model, and hence style his own hair in a similar manner and to live his life based on how he believed his hero would act. Josuke's admiration is so strong that when someone insults his pompadour, Josuke takes it as an insult to his hero and beats up whoever insulted his hair.
- Yukako Yamagishi: The two did not start off on good terms due to Yukako's initial obsession and kidnapping of Koichi. When Josuke saw her again, he threatened to kill her if she did anything to Koichi, though she promised not to. The two were stated to have a relationship where they don't care for each other, but after she and Koichi begin dating, Josuke was seen hanging with her and Okuyasu at a cafe in Chapter 371 (notably without Koichi).
- Shigekiyo Yangu: Initially, Shigekiyo was friendly to Josuke and Okuyasu as he was glad to make new friends. Josuke and Okuyasu referred to him as "Shigechi". Together, they decided to use Shigechi's powers to their advantage to earn some easy money. However, when Shigechi got greedy and failed to keep his promise of sharing an equal amount of money with Josuke and Okuyasu, it led to a confrontation. Josuke and Okuyasu managed to defeat him and Shigechi re-befriended the two. While still annoyed by his greed, Josuke was distraught upon learning Shigechi was murdered by Kira and swore to get revenge for him.
- Yuya Fungami: The two initially started out as enemies as Yuya used his Stand to absorb nutrients from both Rohan and him. Since he was injured, Josuke healed his wounds so that it would be a "fair fight" and then immediately punched him again several times, knocking him out the window. However, when Terunosuke captured Koichi, Josuke went to Yuya for help finding Koichi with his sense of smell in exchange for Josuke healing his wounds. Yuya agreed but stated he wouldn't help fight the Stand user. Despite this, Yuya put his life on the line to save Josuke and Koichi, earning Josuke's respect. The two soon became friends afterwards.
- Reimi Sugimoto: While Josuke did not have much interaction with Reimi as much as she did with Rohan and Koichi, he did still seem to care for her and felt sorry for her condition. He also didn't seem scared of her, despite his initial fear of ghosts. He listened to her advice about the serial killer Stand user Kira and bid her farewell when she left.
- Hayato Kawajiri: Hayato found out his father was replaced by Kira and when trying to expose Kira ended up being saved by Josuke. He gave advice to Josuke throughout his fight with Kira despite not having a Stand, such as exposing a weakness in Kira's Stand ability. Josuke in turn admires Hayato's bravery, such as when he allows himself to set off the bomb on Okuyasu's body in place of Josuke, as Hayato sees Josuke and his allies as the only way to stop Kira. He played an integral part in helping Josuke fight against Kira while Josuke protected him, becoming friends in the process.
- Tomoko Higashikata: Josuke is very close to his mother, as her emotions towards Joseph are much of the reason for his animosity towards his father. He considers her a strong woman and the two love each other deeply. Though he loves his mother, he can be annoyed by her strictness such as telling him to go to bed early or when she froze his bank account after learning he earned 1 billion yen. Both act very informally with each other.
- Ryohei Higashikata: Josuke respects his maternal grandfather and looks up to him due to his profession as a police officer. The two are very close and Ryohei has an habit of pranking Josuke. When he was killed by Angelo, Josuke got his revenge by fusing Angelo to a rock for eternity to stay in the town his grandfather protected.
- Jotaro Kujo: Despite having fought Jotaro when they first met, Josuke has quickly grown to trust him especially after their battle with Angelo and after Jotaro tells him the details behind Stand users in Morioh. Later, when Jotaro takes him out hunting, Josuke is quick to accept, and trusts his strategy. They also band together to fight against Yoshikage Kira. Although Josuke is Jotaro's uncle, he looks up to Jotaro as a mentor while Jotaro cares for Josuke as a younger brother, though is also mildly exasperated by Josuke's temper and Stand abilities. The two have been described as having a relationship of mutual trust and respect, though Josuke tends to feel pressured by Jotaro due to his greater experience and power. He also looks up to Jotaro calling his Star Platinum invincible during his fight with Akira Otoishi and again when fighting Yoshihiro Kira.
- Joseph Joestar: Before meeting his father, Josuke preferred that he would just leave because he thought it was too late for Joseph to get involved with him and his mother. Josuke states that he doesn't hate him, but it would be awkward meeting him now and would rather have him leave them in peace as it's always been. However, he fights against Akira to protect Joseph's life because he believes he'll be seeing bad dreams if he isn't able to help his father. When Joseph first arrives at Morioh with a broken cane, Josuke also helps him walk by holding his hand instead of repairing it. Upon seeing Joseph's strong desire to help people when he endangered his life to save Shizuka, Josuke starts to warm up to him. By the end of the manga, he's happily accepting of his father, though still steals his wallet.
- Shizuka Joestar: When he and Joseph found her, they were surprised by her powers and did their best to take care of her and find her parents. Josuke was concerned when her powers caused her and everything around her to turn invisible and did his best to make sure she was unharmed. He also thinks of her as cute. Considering the limited interactions between the two, it is safe to assume the two get along, especially now that they are siblings (as Joseph adopted her).
- Yoshikage Kira: After Kira killed Shigechi, Josuke swore to avenge him and developed a grudge against Kira. While Josuke loathed Kira, the latter didn't think much of Josuke and as an enemy, preferred to avoid any confrontation with him. However, during their final battle, Kira noticed that Josuke's ability to repair things was the perfect counter to Killer Queen's ability. After realizing that Josuke is the most terrifying person getting in the way of his peace of mind rather than Jotaro, Kira was more cautious during their fight.
- Yoshihiro Kira: Because Yoshihiro is Yoshikage's greatest ally, Josuke and Yoshihiro are enemies. Josuke bears a grudge against Yoshihiro and the latter made several attempts to kill Josuke including attacking him with his Stand and creating several Stand users. Josuke manages to kill Yoshihiro by tricking Yoshikage, who unknowingly makes his father explode.
- Anjuro Katagiri: Due to Angelo murdering his grandfather, Josuke despised him and made a vow to protect Morioh from criminals like him. Josuke would later take his revenge by turning Angelo into a rock.
- Akira Otoishi: Out of empathy for Okuyasu losing his brother to Akira, Josuke disliked Akira and knew he had to be stopped. When confronting Josuke in his own home, Akira underestimated his abilities and thought he could defeat Josuke with only his pinky. When Akira threatens to murder Joseph, Josuke fights seriously against him and after his defeat, Akira cooperates by staying in prison due to fear of being hunted down by Jotaro.
- Terunosuke Miyamoto: In order to lure out Josuke, Terunosuke trapped Josuke's mother and Koichi inside pieces of paper. Josuke was angered by him for being someone who would take people hostage, most notably his mother. Josuke would later get his revenge by turning Terunosuke into a book and leaving him in the Morioh library.
- Keicho Nijimura: Josuke and Keicho met as enemies due to the latter's involvement in putting Morioh's population in danger and shooting Koichi in the throat. While Josuke detested Keicho's callousness toward his own brother, he felt sympathetic towards the brothers after learning of their father's fate, recognizing some decency in Keicho and offered a truce. Keicho, plagued by the thought of his past crimes, rejected the truce and was killed by Akira soon afterwards.
- Toyohiro Kanedaichi: Originally acting friendly towards Josuke, Toyohiro reveals that his kindness was only a ploy in an attempt to kill him. After a brief fight, Toyohiro tells Josuke and the others that he is trapped by his Stand and was just trying to escape. He then dropped all hostility towards Josuke and his friends and informed him that Koichi was being attacked by another Stand user.
The Book: JoJo's Bizarre Adventure 4th Another Day
- Takuma Hasumi: After learning that there was another murderer in Morioh, Josuke went on an investigation that eventually led him to confront Takuma. While the two have only brief interactions, Josuke was angry at Takuma for assaulting Okuyasu and his mother and insulting his hero. In the end Josuke unintentionally killed him by pushing him off a roof.
Relationships in Eyes of Heaven
(The information below derives from a Video Game not written by Araki. As such, it may not be considered canon.)