Koichi Hirose (Echoes) (広瀬康一（エコーズ） Hirose Kōichi (Ekōzu)) is the eightieth episode of the JoJo's Bizarre Adventure anime and the sixth episode of Diamond Is Unbreakable. It covers Chapter 284 through Chapter 288 of the manga.
Koichi is gleefully riding on his new bike to school when suddenly he runs over a strange bag then hears faint meows and sees a dark liquid oozing from the bag. Koichi understands that he has just run over a cat and a stranger named Tamami Kobayashi tries to extort 500,000 yen out of Koichi with his Stand, The Lock. Tamami which works on guilt, and will automatically grow when the victim feels guilty. Suddenly, Josuke and Okuyasu who have seen the two from afar appear to rescue Koichi. While Tamami manages to make Okuyasu feel guilty after punching him, Josuke uncovers a toy cat from the bag and heals Tamami with Crazy Diamond, exposing his schemes and making The Locks disappear from Koichi and Okuyasu's chests. However Tamami flees and steals Koichi's 7,000 yen. Around 4:07 PM, Koichi comes back home, and sees with shock that Tamami is massaging his mother's shoulder and chatting with her.
Screaming at Tamami what he is doing here, Koichi is presented the 7,000 yen Tamami stole from him and is now pretending to return. Tamami adds that when Koichi bumped into him with his bicycle, they exchanged their wallet, and Tamami claims that his contained over 500,000 yen. Tamami successufully makes Koichi's mother feel guilty and The Lock appears on her. When Koichi's sister appears with The Lock on her chest too, this enrages Koichi who pushes his mother and sister out of the room and summons his Stand, which hatches Echoes. Echoes is incredibly weak, but instead creates several loud noises by planting sounds on Tamami, which drive him crazy. However Tamami refuses to surrender and stabs himself, throwing the knife toward Koichi. When Koichi's family barges into the family room, they see Koichi having seemingly stabbed Tamami. The guilt makes Koichi's sister faint and his mother try to kill herself, but Koichi uses the sound "Believe me!" to relieve his mother of the guilt. His Stand defeated, Tamami yields and begs a more confident and assertive Koichi to spare him.
The next day, Josuke and Okuyasu see Tamami sucking up to Koichi and wonder what happened between them.
- Tamami is introduced already slimmed down and short, as opposed to his burly muscular build and subsequent shrinking after being beaten by Koichi in the manga.
- Added introduction by Morioh Town Radio.
- Many graffiti tags are added, especially on the road where Tamami meets Koichi.
- In the official English subs, this episode's title is changed to "Koichi Hirose (Reverb)" to match Echoes's name change to "Reverb".
- On Morioh Town Radio, Kai Harada can be heard reading a write-in letter from the alias "RIP Big Bro" and then wondering how his brother died. This letter is most likely from Okuyasu.
- STAND CARD(S): The Lock
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