Satsuki is a teacher at the same high school as her colleague, Tairaku, who develops romantic feelings for her and expresses his desire to marry her someday. They date, including visits to a local food stall. During one such outing, she and Tairaku witness a young girl, later identified as Aya Shirakaba, smoking alone. This observation leads Tairaku to confront Aya and become involved in her complex situation. Satsuki faces external societal pressure to marry a doctor due to her age, 24, creating tension in her relationship with Tairaku. She remains initially unaware that Aya, pressured by her yakuza father, moves into Tairaku's apartment. When Satsuki discovers this cohabitation between teacher and student, she views it as professionally and ethically inappropriate, causing significant conflict. Characterized as sweet-natured and embodying traditional values, Satsuki contrasts with the chaotic situations surrounding Tairaku and Aya. Her presence represents a sense of normalcy and conventional romance amidst the escalating complications in Tairaku's life.