Ryo is sent out by the people of a village to kill the monster which has been attacking the villagers. It is rumored that this monster is a cat-woman named Bagi. As Ryo waits for the monster to come to its watering hole, he thinks back to how he first met Bagi as a kitten who learned how to write, and later reenters his life on a quest to discover who and what she really is. But now she has gone wild, and as the time of her arrival approaches, he strengthens his resolve to kill her.

It all begins with the story that was left untold—the earth-shattering incident where Renton's father disappeared. With the mysterious pilot Eureka by his side, only Adroc Thurston could undo his own mistake, sparking the event that changed everything and earned him the title of a hero. Now, ten years later, Eureka lies in critical condition as Renton leaves the crew of the Gekko. But when he finds himself in the care of his father's old friends, he has a choice to make. Either stay with the loving family he's always wanted, or earn the love he seeks.

After years of war against the monstrous kaiju, the world finally knows a time of prosperity and peace — but the presence of the kaiju can still be felt. Girls with the souls of kaiju are born every so often, and each is gifted with the unusual abilities of kaiju! An organization called GIRLS has collected the Kaiju Girls to defend the earth, but rising from the shadows comes BLACK STARS, a troupe of evil Kaiju Girls who just recruited their latest — and somewhat bewildered — new member…

Ritsuka Tachibana. She lives a calm and unchanging life. Ritsuka's older brother Lindo returns from studying abroad in the United Kingdom. Shikou Academy student council president Rem Kaginuki calls on the girl, and she begins having mysterious encounters with the student council members. Her life changed a little from that day, but Ritsuka expected nothing more. However, she comes home to find her mother collapsed with suspicious hooded men nearby. They were not human but devils, vampires, and exorcists seeking the Forbidden Grimoire. Ritsuka's former daily life crumbles around her, and she finds herself slowly becoming attracted to Rem, who helps her in her predicament. On the other hand, confusion deepens with regard to her brother who carries a secret. Ritsuka is unsure what path to choose as she finds herself at the center of a love story.