On the final day before summer break, Kenta receives an enigmatic note that draws him to the shuttered school building after hours. There he joins Jinpachi, Miyuki, Rika, Kotomi, Akemi, Ms. Kumi, Munemitsu and Mio, all summoned by the same mysterious message. What begins as lighthearted speculation about a prank quickly turns tense when the entrance is sealed from outside. As the group searches for a way out, Rika suddenly vanishes, leaving the others to confront an unsettling silence and the first stirrings of dread.