Nonomiya Rinka

She is the eldest daughter of the Nonomiya family and the school nurse at the school Hiroya attends. She also teaches the subject of sexuality between men and women in the "Love Community Studies" course. Due to her cool appearance and straightforward way of speaking, she is popular with students, and female students often come to her for advice about their troubles during lunch break. She scolds them properly when they do something wrong.

Although she thinks she is quite strict with Hiroya, she also has some lenient sides, such as buying him the latest model smartphone. Even though they are not related by blood, she regards them as "sister and brother," and she disciplines herself by never overstepping that line.

"Whatever a brother does is my responsibility as an older sister. It is my duty as an older sister to guide him."