Haruyoshi Kugano

Haruyoshi Kugano was the previous identity of the protagonist in his previous life, a man who was touted as the strongest onmyouji of all time. He didn't care about his surroundings and continued to greedily seek power. He had a gentle side, such as taking an orphan as his disciple and loving Yuki, who lacks ability as a ghost, but his excessive power was seen as dangerous, and he was defeated by his beloved disciple due the conspiracy of the Imperial Court.

Source: Official Website

Appearance
Haruyoshi had long black hair and eyes. He wore a typical exorcism outfit of his time period.

Trivia

 * Haruyoshi's spell accidentally sent his soul into a another world, where his new vessel, Seika Lamprogue, is a half demon. As Zor saw Seika have the title "Most Terrible Demon King", Haruyoshi either swapped worlds with the Demon King's soul (resulting in the Demon King reborn as a powerless human in Japan) or the addition of his soul to that world's reincarnation cycle broke the cycle of rebirth for the Hero and Demon King.
 * Amyu is a battle junkie with a perverted imagination, something not hero-like; making it possible the Demon King's soul was reborn in the Hero's body instead.
 * Its also possible the genuine Demon King was supposed to have Seika as his vessel, but Haruyoshi's unintentionded interference resulted in the Demon King being reborn as a nobody.