Hyo Imawano is the main villain and true final boss of Rival Schools, reappearing again in the sequel Project Justice.
Hyo was a high-school student on Justice High School and member of the Imawano Clan, which served the mysterious Darkside Society Organization. Seeking to further the organization's goals to take over Japan, Hyo brainwashes his uncle Raizo Imawano, the principal of Justice High, which starts a chain of events leading to many kidnappings and attacks to students and staff members of various high schools, prompting various students to look for the culprit and being mistakenly led to Justice and Raizo. Three students of Taiyo High, Batsu (Raizo's son), Hinata and Kyosuke (Hyo's brother), confront Raizo and defeat him, so Hyo reveals himself and his plans, only to be defeated by his own brother.
Unknown to everyone at that point, Hyo had been brainwashed by his father since a child, which made him develop a father-complex. After being defeated, Hyo snaps out of his brainwashing and leaves his brother, returning to his life as a student in Justice High.
Because of Hyo's failure, the DSO targets the entire Imawano clan to be killed, including Kyosuke, Batsu and Raizo. They send Kurow Kirishima, who is initially seen brainwashing Hyo. After Kurow is defeated, he orders Hyo to attack the Taiyo students, but Hyo reveals he was not affected at all by his brainwashing, pretending this whole time only to see how far Kurow could go with his ambition. The two have a brief fight, but Hyo easily defeats Kurow, who is left severely injured.
However, Kurow accidentally breaks the seal upon Hyo's sword, which imprisoned the spirit of Hyo's father. Hyo gets possessed by the spirit of his deceased father, transforming into "Demon Hyo" and setting the entire Justice High ablaze. He begs Kyosuke and his friends to defeat him before his father fully takes over, being once again defeated by his brother Kyosuke. Hyo dies on Kyosuke's arms, shortly after his father's spirit leaves his body.