As a child, Amasawa Rei had attended Shirohato Park Institution. After her parents were killed in a car accident, she lived at the institution and befriended a boy. She doesn't remember anything from the time she spent at the institution, not names, not faces, nothing, only that she and the boy shared a secret–a secret much darker than she thinks it is. Now, as a new student at Shirohato Academy with her old classmates from the Park, she is assailed by fragmented memories of the past. What was the secret? Why does she feel driven to find that nameless boy? And most importantly, why doesn't Rei remember anything from her past?

Reki Asubino possesses a cursed mark on his hand. Because of it, neighbors and classmates avoid him; his parents have left him as well. Reki may be the only person left inside the Devil’s Mansion… but he’s not alone. He has a lot of servants in his house… however, they’re just not human. He was given as many presents as he would please, but what he really wants is a human companion. One day, he finally gets what he had always wanted inside a box, literally. Though Reki didn’t only get a human, but also a caring teacher… and a dear friend… or did he?

Hanzaki Academy, an elite girls-only school which combine junior and senior high schools alike; In one dormitory resides Ibaraki Kyou, acting as the leader of said dorm despite her being a freshman. Transferred to the same school, the trouble student — Tsukumozaka Kuroe, how will they face the occult-like development to come?