In the summer of 2015 in Tokyo, Japan. Ryoichi dreamed of becoming a punk rocker when he was younger but became a timid salaryman at a musical instrument parts company. He has feelings for her, but he can't tell her how he feels.. One day, he has a fateful meeting with a turtle on the rooftop of a department store. He names the turtle Pikadon and he adores it, but his co-workers laugh at him. Ryoichi throws Pikadon into the toilet. He regrets what he did. The turtle though goes through sewerage and meets an old man who lives underground. Something then happens.