Hakyō Rukai.
A man, 30 years old, 184 cm tall. His university major was biology, and he even pursued graduate studies to conduct research. He agonized right up until the last moment about becoming a researcher, but ultimately became a high school teacher. He wears thin black-framed glasses, has black hair styled in a soft, permed bob, and wears a shirt with a vest.
He speaks using polite language—“Mr./Ms. ○○.” His classes are serious.