[Zukaishiki (Kaito Shirou)] That Day That Person [ShotaYuu]

A young boy caught sneaking off with a mysterious book finds an unexpected protector when a slightly older stranger steps in, claiming to know him—but the truth is far stranger than brotherhood. The newcomer is none other than his future self, having crossed time to stand face-to-face with the innocence he once was, and what begins as playful introductions slowly gives way to something neither can take back. Patient, knowing hands guide his younger self onto the bed for an encounter that blurs every line between stranger, brother, and self.