Christmas vacation at a private girls' school. Ruby Kanosa is unable to return home due to her parents' circumstances and stays at school. The only other person left in the vast school is 'that' Steel Stepf. During the Christmas vacation, Ruby and Stepf find themselves alone together at school, and Ruby starts to take an interest in her...?! A story of two girls and a fateful encounter, illustrated by Asumiko Nakamura.