Tetsushi Kaji is a student in the same grade as Ayu Tateishi and Nina Sakura at Hideo Middle School. He occupies a prominent social position as the school idol, celebrated for his cool and good-looking appearance and a consistent, friendly smile that he offers to everyone. This popularity ensures he is constantly showered with gifts from a wide circle of admirers, including students from the third grade. This charming and approachable exterior, however, is a meticulously maintained facade. In truth, he is at heart an introverted individual who dislikes the attention and holds a particular distaste for receiving presents from strangers. He guards his genuine feelings and private thoughts closely, seldom allowing others a glimpse behind the mask. The driving force behind his "nice person" persona is his romantic affection for Ayu Tateishi. He strives to uphold this image because Ayu once told him she liked that kind of person. His dynamic with Nina Sakura shifts when she alone discovers the true nature hidden behind his popular facade, an event that draws the two of them closer. He is a member of the school's baseball club, where he is recognized as the team's ace. His best friend is Hiroki Tsujiai, the captain of the boys' tennis club. His documented storyline culminates in him eventually beginning a romantic relationship with Ayu Tateishi.