Miki loses her mysterious bell-shaped object, that her school friend picks up. As they return home by bus, inexplicably the brakes fail, the bus rolls into a long dark tunnel, transporting the two girls into another world. As Miki awakens, she sees wolf-faced warriors abduct her friend — apparently to kidnap the girl with the bell, but taking the wrong girl. Miki tries to follow the strange monsters, to save her friend, but fails — trapped in a world of monsters and madmen, who plot the downfall of Earth.

The only power that can possibly save her (and the world) is that of the mysterious Mask of Zeguy. Miki must embark on a life-threatening quest for this talisman, with the villains in hot pursuit!