A young woman preparing to take high school entrance exams at the beginning of the story. Tired out, she falls asleep in the snow one day and is discovered by Kai, who she immediately becomes close to when he decides to tutor her. They fall in love, but Kai stands her up after promising to meet her after she gets her exam results. The same day as she is stood up, she meets Takami, who she congratulates on also passing. They are classmates from then on, and Takami develops a great deal of affection for her since she was the only one to congratulate him for passing.
One day she follows Takami and discovers him visiting Kai's grave. Takami is forced to explain that he is Kai's younger brother, and Kai, fatally ill, had asked him to take care of Atsuki if he should die. The revelation puts some distance between them, but Atsuki and Takami come to terms with their own feelings and confess their mutual love.