Kouichi Azuma, known as Azuma-sensei, teaches the main student group at Homare High School. He possesses naturally gray hair and wears oval-shaped glasses, contributing to a handsome appearance that draws attention from female students, though he remains unmarried. Azuma is characterized as reliable and composed, earning him popularity and respect among the student body. One student specifically noted his perceived popularity during the Cultural Festival, while others described him as down-to-earth and kind, qualities they contrasted with their expectations of another person.

Azuma shares a long-standing childhood friendship with Akira. At age 17, both participated in a high school work experience program at Hidamari Kindergarten. There, Azuma's kindness towards their kindergarten teacher, Kaori-sensei, inadvertently provoked jealousy in a young Kaname Tsukahara, creating conflict. This childhood friction resolved positively over time. Azuma pursued a career in education and eventually secured his teaching position at Homare High School. Kaname, now a student at Homare, recognized Azuma as the student-teacher from his kindergarten days. However, Azuma has not connected Kaname's identity to that specific childhood incident. His professional demeanor remains consistent within his teaching responsibilities.