Sheer Heart Attack, Part 6 (シアーハートアタック その⑥ Shiā Hāto Atakku Sono 6), originally ACT3's "Ability"!! (ACT3の『能力』!! ACT3 no "Nōryoku"!!) in the WSJ release, is the three hundred fifty-ninth chapter of the JoJo's Bizarre Adventure manga. It is also the ninety-fourth chapter of Diamond Is Unbreakable.
After having summoned Echoes ACT 3, Koichi asks it to defend him and an unconscious Jotaro from Sheer Heart Attack. Echoes then dashes in front of Koichi, and adopting a fighting stance, punches the miniature tank. Yet Echoes is overpowered and knocked away. Koichi witnesses his Stand being defeated and begins to panic, but soon sees that Sheer Heart Attack has sunk into the ground and is completely immobilized. Meanwhile at a nearby café, Kira's left hand becomes suddenly heavy and it inadvertently crushes a coffee cup. Kira's public humiliation continues when he undresses a waiter by accident and he decides to check on Sheer Heart Attack himself. Meanwhile Josuke and Okuyasu are running towards Koichi's location.