A drug has been spreading in secret lately, turning anyone who uses it into a kaijin with special powers. The Agency captures these kaijin and turns them back to normal, and its top agent is a transforming heroine called Meteor Battle Princess Holy Astel. Astel is Kaori Hoshimiya, who gained the power to transform through the Agency's technology. Her boyfriend, Noboru Yuuzaki, fights at her side, supporting her with combat drones. But while the Agency cracks down on kaijin, an organization is spreading the kaijin transformation drug.

This organization indulges in twisted games, like betting on whether Astel or the kaijin will win. It has even started taking bets on whether Kaori will be stolen away from Noboru. Can Kaori and Noboru bring down the organization without anything happening to them?