The Dragonfly Undead kidnaps Amane and her mother, intending to lure Hajime into a trap. Isaka's Rider System is complete, and all that remains is finding a compatible host.

Tachibana retires as Garren, after his involvement in the creation of Isaka's Rider System. That night, the Leangle belt goes missing.

Leangle has found a host, and within minutes reveals a dangerous new ability. Who has succumbed to the power of the evil belt?