Yoru wo Utau Kodomo-tachi

Overview

“Those who meet the owner of the secret mansion never return to their world again…” Students mysteriously disappear one after another from the campus, for which the rumors say that has a secret door hidden somewhere. This time the mising person is Kuniyuki’s best friend - Kashiwagi. Are the rumors really true? Kuniyuki is angry and has no idea what to do about his friend, when he meets a strange, but very pretty girl called Towa. She says she is the guardian of the “outcasts,” those who were taken to the “mansion,” but what does that really mean...?!

Source: AniList