Kaori's childhood friend, classmate and club mate in the astronomy club. At the start of the story, Kaori found herself struggling with her secret feelings for Sou, as he seemed completely oblivious to them. Saddened by several events showing that obliviousness, she began punishing Sou by sulking for a few days, until the members of the Astronomy Club went to see the stars together one night and the other three club members left them alone for a while to make up - expecting they would have a romantic moment together beneath the stars, which ultimately did not end up being the case. Kaori forgave Sou either way, since he apologized for whatever he may have done wrong, even if he still did not understand what she was mad about in the first place. The next day, she finally took the courage to confess to him. Perplexed by the sudden confession, Sou tried to describe how he feels about Kaori, yet had troubles to do so, thus Kaori allowed him to think about it a little more and told him that she would patiently wait for his answer.