He is a 13yearold boy who lives alone with his father. He is curious, shy, and introspective. Shinji frequently thinks about his 31yearold neighbor, Cai Yaru, finding her unexpected appearance in a revealing attire captivating. His mind often wanders during classes, and he struggles with attention span. He experiences his first stirrings of adolescence upon seeing Cai, discovering new feelings that confuse and excite him.
She is a 31yearold teacher at a local high school in Japan. She is confident, mature, and independent. Cai frequently receives packages at her doorstep, which causes brief moments of unexpected encounters with her neighbor Shinji. Her appearance leaves an impression on Shinji, marking the beginning of his adolescent infatuation. Despite these minor interactions, her daily life remains focused on work and personal routines, showcasing her dedication to teaching and her busy lifestyle.