Kyosuke doesn't recall the faces of his parents as they divorced when he was young. He only remembers being with his older sister, and they lived together in a small village. His sister juggled with being an university student and various part-time jobs to support them. Kyosuke also worked to lessen the burden on his sister. One day, his sister brought to their home a man who introduced himself as Osaki. The fifteen-year-old Kyosuke didn't trust this mysterious new man and ran away from their home to be alone. Osaki followed him and told him to return before his sister worried. As Osaki offered to bring the boy to his feet, he unleashed a wave of power that frightened Kyosuke. Osaki, who was impressed with the boy's hidden power, manipulated Kyosuke's sister to eventually become their brother-in-law.
When Kyosuke was returning home from his part-time job, Osaki greeted him. He wanted to unleash Kyosuke's true power and therefore killed his older sister. Osaki disappeared and Kyosuke dedicated himself to avenging his loss. In his ending, he isn't seen escaping from the explosion caused by Ohga and presumably dies. Kash, Isato, and Ikki watch the explosion from afar and roughly imply that it was Kyosuke's choice to stay.
Kyosuke is a quiet yet sincere individual who doesn't like to reveal too many details about himself. He refers to his sister's death as a horrible nightmare and feels as though half of him has died with her. He fights to regain his will to live once more.
- Summon spirits - Kyosuke can summon three animal spirits to fight with him. He can order a wolf (Kubira) to maul and electrocute foes. He can order a hawk (Basara) to dive down and burn opponents with a fireball. He can order a monkey (Mokora) to attack his enemies. The fourth spirit he can summon (Gaia) can briefly materialize itself as a muscular man to damage anyone around Kyosuke.
- Shadow attack - Kyosuke can throw his shadow like a whip using his sword.
- Kuzureru Suna (Crumbling Sand) - Voltage Fighter Gowcaizer
- LONELY LOVE - Hybrid Vocal Collection image song
- Ryōtarō Okiayu - Voltage Fighter Gowcaizer game and anime
- Yusuke Sakamoto - Hybrid Vocal Collection singer
- Joseph Morgan - Voltage Fighter Gowcaizer anime (English voice)