Kimi no Nemureru Kaii no Kousha

A supernatural force traps four students in a dilapidated school building on their second day at school. If they don’t solve seven different mysteries before the sun rises the next morning, they’ll be stuck there forever?! Takuma Sakai, author of Butareba -The Story of a Man Turned into a Pig-, delivers a suspenseful supernatural boy-meets-girl mystery! (Source: Manga UP!)