Kengi was a Makai Knight that was killed and imprisoned by Karma, the father of Rekka and one of the mentors of Kouga Saejima. He first appeared in Red Requiem and later The Tougen Flute, always as a guardian spirit to Rekka.
Little is known about Kengi due to limited observation. He seemed to have been a wise warrior and had a deep affection for both his daughter and his duty as a knight. During his free time, he enjoyed playing his flute. After his demise at the hands of Karma, he remained as a trapped and tormented spirit within Karma's realm. After the intervention of Rekka and Kouga, he was freed and chose to watch over his daughter as a guardian spirit, only acting in her most desperate hour.
Sometime after training Kouga, giving the youth the moral code he lives by, Kengi was assigned to hunt down the Horror Karma. However, like those before him, it ended with Kengi devoured and his soul trapped in Karma's realm. But during the events of Red Requiem, Kengi's soul was freed and he and the other Makai Knights lend Kouga their power to strengthen the Garo Armor to destroy Karma. In the events of Tougen Flute, Kengi appeared before Rekka to give her words of encouragement when she was between life and death.
- Makai Knight Training: Kengi was a trained Makai Knight; it is unclear the depth of his abilities.
- Makai Blade: As a Makai Knight, Kengi wields a soul metal sword in the form of a Chinese Jian; his armor and title were never revealed.
- Kanji Tsuda also portrays Tousei Kaneshiro in The One Who Shines in the Darkness and Daisuke Okubo from Kamen Rider Ryuki.
- Given his sword and the fact he was chosen to train the future Garo it is highly likely that he was a Titled Knight or at the very least, a Titleless Knight who managed to attain a sufficiently great pedigree to train a Titled trainee.