Hikari Asano

On a cold winter's night, a man finds two girls—Saori and Shiori Mizuki—seemingly lost in front of his apartment. Since then, the twins have gradually become attached to him, with one staying at his place while the other is at school. However, the sisters' relationship with him is not merely that of a babysitter and child because sometimes more mature events occur.

Akira Sakagami was preparing to ask his classmate Nana Shirayuki out on a date when his sister Rio suddenly arrives, moving back in with Akira due to her housing situation. This complicates things because Rio was his first love. Then, Rio points out that Shirayuki looks really similar to her. Now he can't help but see Shirayuiki as his sister.