Diamond is Unbreakable - Chapter 90 
Sheer Heart Attack, Part 2 (シアーハートアタック その②, Shiā Hāto Atakku Sono 2), originally Observe Carefully!! (注意深く観察しろ!!, Chūibukaku Kansatsushiro!!) in the WSJ release, is the ninetieth chapter of Diamond is Unbreakable and the three hundred fifty-fifth chapter of the JoJo's Bizarre Adventure manga.
Koichi tries to dash toward the killer but is stopped by Jotaro, who warns him about possible traps. Sheer Heart Attack effectively explodes, narrowly wounding both Jotaro and Koichi and disintegrating the shop owner. Moreover, Koichi hears a door shutting, meaning that the killer got away, and wants to chase him, but Jotaro advises to ponder their move, being certain that Sheer Heart Attack is still present. Koichi is skeptical, and lets his guard down, letting the substand take him by surprise. It jumps on Koichi's head and begins to roll on him, hurting him with its threads. Jotaro summons Star Platinum who heavily pummels Sheer Heart Attack, but it surprisingly remains unscathed. Koichi warns Jotaro that touching it may trigger an explosion, thus Jotaro stops time and pummels it even more heavily and punches it into the ground. Unfortunately, Sheer Heart Attack leaps out of its hole and goes to attack again, being invulnerable to Star Platinum's might.