Aoi Yui

Interests: collecting pillows, sleeping
Skills: sprinting
Favorite food: meat

The protagonist's twin sister. Cheerful and approachable girl, she is naturally bright that even if she just transferred, she is still the center point. She thinks similarly to the protagonist, specializes in concern and attention surrounding their atmosphere. Used to attend an all girls school, but because she is unable to stand the atmosphere there, she transferred to the protagonist's side.