During her summer holiday at her grandparents house Tamai Shiina, a young and cheerful schoolgirl, meets a strange looking creature. They befriend each other and Shiina names it "Hoshimaru: The Round Star." When Shiina returns home after the summer to go back to school, she starts meeting other kids that also have befriended a strange creature like Hoshimaru. But she soon finds out that not all these creatures and their masters are as friendly as Hoshimaru.

The story circulates around a mysterious and dangerous island referred to simply as "G". A long time ago, a powerful god named Gestalt was banished to the earth and he had found refuge in the island known as G. To utter the name for which it stands is forbidden, for people were so afraid of the wrath of the god that they considered his name a curse. Father Oliver is a priest who has left his order and traveled to the island of G in order to discover the truth behind it. He ends up making the acquaintance of a young girl named Ohri, who turns out to be quite adept in magic. Meanwhile, the head of the order has hired a dark elf named, Suzu, to track down Oliver and bring him back. Suzu finds him easily enough. However, she hadn't anticipated the powerful sorceress in his company, Ohri. The girl disposes of Suzu for the moment, and she and the Father continue on. As if things weren't rough enough, the island of G has it's share of monsters and magic-users to get in the way of their travels.

To the unsuspecting eye Maki, Reimi and Yuka may not look like ace crime fighters, which might explain why they're stuck on traffic patrol instead of more "exciting" police duties. All that changes when Yuka gets herself kidnapped by a white slave organization run by a politically connected businessman who's got the rest of the police cowed. Now it's up to Maki and Reimi to don skin-tight battle armor, liberate a tank, and make sure that a certain slaver learns that when you play with fire, you're going to get your ass burned!

A terrible war has ravaged the land, and now, fueled by the blood of numerous fallen warriors the Yoma, demons from hell, emerge once more. A skilled ninja seeks to end the bloodshed these demons inflict upon humanity, but to do this he must fight against his undead former best friend and fellow ninja who was killed in battle and has been resurrected to serve the Yoma.