Math teacher. He always keeps his collar open, because he feels stressed when it gets stuffy around his neck. He never buttons up for important family celebrations. When one of his students said that "Nobody needs math in the future", he tossed said student out the classroom window like in Smash Bros and this became known as the Smash Bros. Incident. There was a "Kill Sanemi-sensei" plot for a while, but after the Smash Bros incident that plan disappeared. He's very kind to women and kids