Three months have passed since the Demon King was defeated by a hero. Mankind rejoices over their victory, but dwellers of the demon world do not share the same sentiment. With the loss of their king, they must now hold a tournament to decide who will become his successor. Monitoring the competition is the hot-headed yet powerful Vamirio—one of the Four Heavenly Kings. Among all the participants, she is extremely distrustful of one: Helck, a human hero who claims to hate humanity. As much as she wants to get rid of him, it is impossible due to Helck's incredible strength and popularity. Amidst the competition, Vamirio discovers that humans have vanished from various towns. As a result of this puzzling turn of events, Vamirio grows desperate to reveal Helck's true intentions by carefully crafting a plan to make Helck lose. If she proves to be successful, she might uncover where his loyalty truly lies before the demon world is endangered.

In 19th-century France, the wife of vampire noble Jean Duchet Godard is murdered in her own home. With the local human authorities unwilling to properly investigate the case, Godard hires a pair of private detectives known to specialize in the supernatural: Tsugaru Shinuchi, a man with a mysterious birdcage; and his partner, Aya Rindou. This enigmatic duo has come from faraway Japan for one purpose—to track down the man who stole both Aya's body and Tsugaru's humanity.

Akemitsu Akegami was always told by his father that "no one can live alone"...but he's sure determined. After all, his father sure wasn't saying it with the best intentions, and Akemitsu has no desire to become like that creep. But when a chance encounter with a young woman leaves him with thoughts that are all too impure, he decides to do what he must—become a Buddhist monk and renounce worldly ways. But the temple he decides to devote himself to...is full of women? And that same young woman is there, too?? What's a guy to do?

When Saku took in a stray black cat, she never expected that he would become the equivalent of a housekeeping life partner. But Yukichi, a giant cat who towers over Saku, is not your ordinary feline. He takes great pride in his culinary skills, and a good sale at the supermarket always gets his whiskers twitching. Saku may not have her act together yet, but at least she has Yukichi!