Harunobu Nikaidou

Harunobu Nikaidō (二海堂 晴信 Nikaidō Harunobu) is Rei's friend and main rival in shōgi.

Personality
Despite illness having plagued his childhood, Nikaidou has an earnest personality, along with a cheerful outlook towards life. He is described as persistent and stubborn when it comes to his rivalry in Shogi with Rei. However, he does get emotional over his losses, but does his best to keep a strong front while in public. He doesn't give up and even with his illness lets shogi become his life.

Background
Nikaido comes from a wealthy family, but he is born with an incurable disease. He met Rei a long time ago and since then Rei has known him for a long time. He sees Rei as his best friend and rival in shogi.