Matarou, a young man at school, confesses his feelings for his senpai, Mikoto. She invites him over to her house for dinner. While she's making dinner, Matarou looks around the house and collects pieces of Mikoto's diary. As he continues his strange quest, he slowly realizes that Mikoto isn't what she appears to be.
SPOILERS! READ AT YOUR OWN RISK!
Towards the end of the game, Matarou discovers three rotting corpses in Mikoto's closet. From what he had read from the diary entries, he deduced that two of them were Mikoto's parents and the other was Yukimaru, a boy who started dating Mikoto before Matarou. Mikoto then enters the closet and confesses that she locked her parents in her closet and "took care" of them. One day, they called her a demon child and Mikoto refused to feed them for a week. As a result, they starved to death. Some time after their deaths, she met Yukimaru who seemed to give her life meaning again. Like Matarou, he eventually discovered the bodies and she kept him locked in the closet. She then asks Matarou if he'd run away like Yukimaru did.
Bad End: Edit
If Matarou heads into the closet without obtaining the flashlight from the box in the storage room, Mikoto will enter and hit him on the back of the head, probably locking him up too inside the closet.
Bad End 1: From Behind Edit
If Matarou runs away from Mikoto, Mikoto will immediately catch up to him and it's left ambiguously if he was killed by her or if she took him back to her house and locked him up.
Bad End 2: What You Wished For Edit
If Matarou decides to stay with Mikoto, Mikoto tells him that she will bring him lots of food for him and promptly locks him in the closet.
True End Edit
If Matarou hugs Mikoto, Mikoto will be moved by Matarou's actions and starts apologizing for what she had done. Months later, she and Matarou are still together as they start playing in the snow. Matarou fondly notes how Miktoto's behavior had improved since he had accepted her.