Kazuma kills his father in order to protect his mother and younger sister from violence. He begins life at a halfway house with an aim toward social rehabilitation and also works diligently at a scrap mill, but society has labeled him a “murderer”. Gradually, Kazuma loses hope.

Kazuhiko seizes the opportunity of his mother's illness to quit work and return to his parents' home. He begins working at senior citizens' home, performing his duties despite having doubts about the facility's policies even as he listens to his mother's grumblings at home. Then he meets a rebellious woman, Aiko, who begins to have an influence on him.

Granute, secret lifeforms, kidnap humans for "Dark Market Snacks." Shoma, from another world, transforms with Gochizo, a sweet-eating monster, into Kamen Rider Gavv via a mouth-like belt to stop Granute's attacks and save people.