Kyouhei Hioka is a character in Persona x Detective Naoto.
Persona x Detective Naoto
Kyouhei is the older brother of Kaoru Hioka, as well as the mentor and former lover of Touko Aoi. He lived together with his younger sister and worked as a police detective in Yagokoro. After his sister's death, his understanding of the concept of justice changes as he realizes there's no real way for him to pursue those that killed her.
He learns of Kaoru's connection to the Midnight Site from Yuuko Takizawa when he is investigating her death. Abandoning his position, he decides to take justice into his own hands and find the five judges that preside over the site. He is Naoto Shirogane's first suspect when a stranger named Kagutsuchi announces retribution will come upon the remaining four judges after killing the girl behind the judge known as Uzume, Miyuki Midorikawa.
However, it is revealed that Kyouhei has been dead even before Naoto's involvement in the case, having been killed by Shirou Konno. Kyouhei's death propels Touko Aoi into action as she decides to finish the work he started.