Hagiura Aina

The twin sister of Yuuna, who is the reason why the protagonist had to change school, and a teacher at the academy.
The primary target of the protagonist, she has a calm and caring personality, but is also headstrong and stubborn and won't falter on any decision she make.
She is still a newbie teacher, and is a bit unreliable, but she is kind to her students.
Normally a follower of her sister, but when push comes to shove, she is shown to have a stronger will then her.

Aina is a virgin with a strong sense of chastity, but once she experienced pleasure, she became exceptionally horny.
Her physical development is better than her sisters, and although she was trained later, her perverted qualities surpass those of her sisters.