Ginka: After

Five years ago, Aoba Ryusei's childhood friend Shinomiya Ginka vanished on the night of the summer festival. The islanders called it being spirited away. Now in high school, Ryusei returns to the island hoping to learn she came back — only to find no one has seen her since. Then he meets a girl who looks exactly like Ginka. She does not know her name. She only knows she loves him. What happened to her, and why has she not aged a single day?