Nirei has messy short blond hair and wide dark brown eyes and brows. Nirei is generally calm and quite cheerful. He has his candid and clumsy side. However, his character changes radically when he has to face danger. Indeed, he becomes much more stressed and frightened, this being due in particular to his past of being bullied and by the fact that he doesn't know how to fight. He also feels rather pathetic about joining Fuurin without a combat skill, though his classmates say otherwise.