Komori Isao (Yoshizawa Ryo) is a university student who has no friends and a tendency to withdraw from the outside world. When he wakes up one morning, he is suddenly inside Yoshizaki Mari (Ikeda Eliza), the beautiful high school girl whom he secretly likes and had been tailing. Only Mari’s classmate Kakiguchi Yori (Nakamura Yurika) realises that a different person is inside. Isao and Yori team up to search for the missing Mari but the mystery only deepens. Relationships start to breakdown and a secret promise is also revealed.