Kensaku Shiraishi (白石 謙作, Shiraishi Kensaku) was Battle Cossack of Battle Fever J before his tragic death.
Raised an orphan, he was once saved by a priest who was taking care of his orphanage and died to protect them from criminals. Since then, Shiraishi had always felt a need to protect those weaker than himself.
His main weapons were twin sais. He was the original second in command into the team. He was good at science as well as war. His hobbies included playing Pachinko, doing a classic Cossack dance, and he enjoyed eating caviar.
Kensaku left Big Baser without his Battle Cossack uniform to spend time with Mayumi, the daughter of his mentor, a researcher with the Defense Department. The Cutmen kidnapped Mayumi while Kensaku left to get shave ice for them. Cornered and without his uniform, Kensaku dodged fire and got Mayumi away, but he was still held at gunpoint. Bravely, he went on a suicide run of attack and was repeatedly shot. His friend Makoto Jin came to rescue. Kensaku's uniform was brought to him, but it was too late. He died surrounded by his team and Mayumi.
Makoto took Kensaku's uniform for himself and replaced him on the team and to avenge his friend's death.
- Battle Shark (shared with Japan, France, Kenya, and America)
- Battle Fever Robo (shared with Japan, France, Kenya, and America)
- Command Bat → Sais
- Cossack Machine