Izuku is accidentally hit by the "Assistant Pet" quirk-a mischievous black blob that shapeshifts and possesses him to conquer his deepest fear-which he has no idea what it is. With his friends' help (and a very reluctant Katsuki leading the charge), Izuku starts crossing off ridiculous fears while the clingy little creature causes daily chaos. But when the truth finally surfaces-that Izuku's real fear has always been confessing his feelings to Katsuki-everything changes. Their easy, playful friendship is perfect... until the pet starts getting dangerous to force the confession. Now Izuku must risk ruining everything he has with his Kacchan, or let the blob choke the life out of him trying.