Age: 11–12

Blood type: AB

Hiro, the sheep of the zodiac, is a very intelligent but verbally aggressive and smart-mouthed sophist. He is in love with Kisa, and resents Tooru because she unwittingly monopolizes Kisa's time and attention. He starts out hostile to Tooru, but eventually eases his initial attitude through a combination of grudging admiration for Tooru and Kisa telling him to let up. He is sarcastic and pessimistic.