Youki died in a traffic accident and was reborn in a fantasy world! However, instead of being the hero of legends, he ended up reincarnating into an overpowered demon. Having no desires to become the Demon Lord, he sits around in the Demon Lord's castle as a random low rank guardian. One day, the Hero's party comes to attack and on a whim he knocks out the entire hero party. Healing up the Hero party and then preparing to send them back to town, he notices the female priest and falls in love at first sight!

Already at his wit's end, 29-year-old corporate slave Seiichirou Kondou suddenly witnesses the ground opening up and swallowing a woman. Amid his efforts to save her, the two are transported to another world. He soon learns that the people in this world summoned a saint to save their kingdom from a plague. As compensation for dragging Kondou into the mess, the kingdom assures him that they will provide him with a comfortable life and fulfill any of his desires. To everyone's surprise, Kondou asks for a job. After successfully becoming an accountant at the Royal Palace, Kondou devotes himself to his new post. His accurate and thorough work catches the attention of various high-ranking officials and knights, especially Aresh Indolark, the cold-hearted Knight Captain. As Kondou adjusts to his new exhausting and dangerous environment, he begins to find solace in the company of Aresh, whose icy demeanor may be just a facade.

Arne Neuntöte is a vampire detective who manipulates supernatural powers. Lynn Reinweiß is a nobleman's daughter who loves vampires. Their worlds should never have crossed, but they join hands to solve a bloody mystery. In the darkest of nights, Lynn finds herself in desperate need of help. Then she wanders into the mysterious city of "Lügenberg," where non-humans live. Lynn's world changes drastically when she encounters "Arne," a vampire who is called "the worst" in the city. And tonight, a new "murder case" has occurred. What is the truth behind the bizarre incidents that take place in a world where humanity and the bizarre intersect? "Come on, human. You may dance merrily under the crimson moon."

Alba is reborn as the son of a poor nobleman. He is unable to use magic due to a disease and is destined to have a short life, so he is taken in by the duke's family. There, he meets Orsis, who was his favorite person in a previous life. While this coincidence seems to good to be true, he remembers that he is why his beloved lost his smile, and begins to search for a way to live a long life so that he can continue to love him.