The Other Side of Secret Vol. 1

See You On The Other Side! Yuuto is a typical teenager who hangs out after school having silly conversations with his friends, but there's something he hasn't told anyone. Seven years ago, his older sister, Manami, disappeared through a mysterious door. Yuuto has searched for her ever since, but hasn't had any luck. One day, the same secret door his sister forbade him to enter appears right before him, and two girls rush out of it! In order to find his missing sister, Yuuto steps into the forbidden world...