Giyuu Tomioka is a Demon Hunter and the Water Pillar of the Demon Slayer Corps.

Hibari is the leader of the Discipline Committee, or Prefects, who all happen to be a group of delinquents loyal to Hibari. Like his subordinates, he too is a violent delinquent who uses his status to harass other students. However, he prefers to be alone and cares little for his subordinates. If he is amongst a crowd, he tends to play violent "games" with rules like "I'll kill anyone who wakes me up when I'm sleeping," and as mentioned, the loser often has to pay the price with his life. His catchphrase is "I'll bite you to death," which he says to everyone who he is ready to fight. In one comic scene, Ryohei misunderstands it and imagines Hibari swallowing Gola Moska's head. He also likes saying "wao," and when he fights weak opponents, he tends to taunt them by calling them a "herbivore." He likes eating Japanese food and hamburgers. Hibari may be a violent and cruel person at times, but he is very proud of his school, and is apparently the only person who likes their school's song, even using it as his ringtone. He has also been shown to have an affinity for birds; he adopts one of the avian followers of Kokuyo assassin Birds' and trained it to chirp his school's song. The bird (subsequently nicknamed "Hibird" due to its connection to Hibari) becomes attached to Hibari, so much so that it still remains with Hibari nine years and ten months into the future. His attitude and abilities have gained the attention of Reborn, who sees him as a potential candidate for Tsuna's family. However, Hibari likes nothing more than to kill those who are in his way or people that are crowding.