Yuuki Sanae

A student-teacher who came to apprentice at the school. She teaches music.
She is a good-natured girl who is unforgiving of crooked attitudes, always tries her best, but is also a total screw-up, and is often unhappy about it.
An alumnus of the school, she is still well-loved by her old teachers.
The protagonist's first target, she is humiliated and raped by him at the beginning of his conquest, and is blackmailed into doing what she's told.
Nevertheless, she tries in vain to rehabilitate the protagonist.