SSSS.Gridman

Yuuta Hibiki, a high school student, wakes up in Rikka Takarada's room with no memories and is addressed by a voice belonging to Hyper Agent Gridman, a robot he finds on an old computer. Rikka cannot see or hear Gridman, nor the monsters she describes as being in a thick fog over the town. A giant monster appears in the city, and during the chaos, Yuuta merges with Gridman and finds himself in the middle of a battle, fighting the monster. Yuuta teams up with Rikka and classmate Shou Utsumi to form the Gridman Alliance and investigate the source of the monsters.