Five young warriors from the ancient civilization of Dinosaur-evolved Humans are awakened in the present day after 170 million years of suspended animation when their sworn enemy, Bandora the Witch, is inadvertently released from her magical container on Planet Nemesis by two astronauts. The five warriors, the Zyurangers, must summon the power of mechanical-looking deities known as the Guardian Beasts, each modeled after a different prehistoric beast, in order to protect mankind from Bandora's evil forces.

The main character and "anti-hero", The Rapeman, is a high school teacher by day and dispenses his surreal brand of "justice" at night under the business "Rapeman Services", which is co-run with his uncle, a former surgeon. He uses rape as his weapon. The business' motto is "Righting wrongs through penetration".