Yomogi Youko

Mathematics teacher at St. Ruri, she is also the advisor of the student council as well as the swimming club.
She lost her parents when young so she was raised in a facility supported by Rentaro whom she admires and respects, that's why she decided to become a teacher and work alongside him.
When she was still living in the facility, Rentarou often visited her alongside Maika, with whom she spent time playing, that's why she knows Maika's secret.
She is a natural airhead and always shows its true nature. She is popular with students because they see her as an older sister and she tends to befriend them.
She is a St. Ruri alumni and held the position of student council president. Despite her calm appearance, she is good at sports and even participated in national swimming competitions.