Sheer Heart Attack, Part 1 (シアーハートアタック その① Shiā Hāto Atakku Sono 1), originally Got a 'Clue'!! (つかんだ「手掛かり」!! Tsukan Da 'Tegakari'!!) in the WSJ release, is the eighty-ninth chapter of Diamond is Unbreakable and the three hundred fifty-fourth chapter of the JoJo's Bizarre Adventure manga.
Koichi meets Jotaro, who is investigating the button left by the mysterious killer. Koichi tries to engage a conversation, but Jotaro's aloofness makes it awkward. Jotaro notices that a shoe shop is accepting simple tailoring requests, and decides to look inside. The owner, upon being asked if he's seen the button, replies that someone did ask him to repair a jacket which has the same button, making Jotaro and Koichi realize that the jacket have found a lead. However the owner doesn't remember the client's name and has to look at the order tag inside the jacket, but before anyone can recognize the name, something takes out a piece of the owner's hand. A miniature tank appears on the owner's shoulder and runs inside his mouth, killing him. Now on their guards, Jotaro and Koichi look around, and Koichi sees a hand taking the jacket, who is Kira trying to erase all traces of himself. Koichi then sees that the miniature tank is up to something.