Andou Kei

Rei's younger brother and a second-year student at the academy. He's average at studies but good at sports. Due to family circumstances (his parents are often absent, so he has to do housework, but his sister pushes everything onto him, leaving him no time for club activities), he isn't in any clubs.

He gets treated pretty badly by his hot-tempered sister, and while others sympathize with him, he still loves his sister. He has a gentle personality and is well-liked within his class.

Because he's good at looking after others, and due to his father's work, he lived in America for a short time as a child. Because of this, he is entrusted with looking after Linda.

It turns out he actually has S-type tendencies rather than M-type.