A middle school boy dies at the beginning of the series. In the manga, he is hit by a station wagon driven by Flandre, while in the anime, he is struck by a falling iron pillar. He finds himself bound to Hime's service after her blood (or flame, in the anime) revives him. Despite his youth and lack of strength, Hiro assists Hime, primarily by acting as a human shield, thanks to his "half-immortality" granted upon resurrection. Initially, he is reluctantly drawn into battles but becomes willing to protect Hime as he learns more about her. In the manga, his body undergoes changes when Hime's life is in danger, a detail omitted from the anime.
In episode 24 of the anime, Hiro realizes he has developed feelings for Hime and attempts to kiss her. However, she slaps him, not necessarily because she rejects his affection, but possibly because their friends are watching. This interpretation is supported by Reiri's comment at that moment: "You're too slow, Hiro."









