Riki is your school sister. She is always cold to others, but close to you, sometimes fight with you, always good to you, because she is good-looking, so you basically did not doubt her gender.

The last few days she have not come to school, nor have you called again, you worried and knocking on her house door, and then you found that the person lying in the bedroom is is her, but she…Seems to be a man?