On the brink of extinction, mankind has downsized and now solely resides in the city-state of Flandore, living in cities encased by glass domes. Beyond the domes exist vicious lycanthropes who thrive in the darkness; among the citizens inside, a clear distinction between the nobility and commoners is in place. The blood of nobles enables them to utilize mana, granting them abilities that exceed human limits and greatly assist them in defeating lycanthropes. Already 13 years of age, noble Melida Angel has yet to manifest her mana, and attends an elite academy where she is mistreated for her lack thereof. In order to help her, Kufa Vampir is ordered by the Angel family to become Melida's tutor. While Kufa seems to be a mere mentor, an ulterior motive lurks behind his job—he is to assassinate her if he confirms that she does not possess mana. Kufa's investigation eventually leads him to determine he must eliminate Melida. However, Kufa is struck by her unwavering determination, spirit, and belief in herself when he witnesses her in a fight, choosing instead to offer a way she can manifest her magic. As Melida learns to use mana with the help of Kufa's teachings, Kufa forsakes his mission and jeopardizes everything to keep his discovery of Melida unknown to the Angel family and his own guild. However, both Kufa and Melida will soon realize that hiding their secret will not be the only challenge they face, as unforeseen trouble is waiting just around the corner.

Valkyries—legendary female warriors from the land of gods, Asgard—are sent by Odin to protect Earth against the growing threat of demons. To overcome these threats, nine valkyries under the guise of the Saotome sisters will have to level up by performing a variety of romantic acts with their official lover, Einherjar. Meanwhile, the socially anxious Takuma Akutsu learns that Odin has chosen him as the valkyries' lover. Despite his utter horror, however, he agrees to let the sisters stay in his big yet empty house to help them in their war against demons. With nine beautiful women sharing his roof, will Takuma manage to prevail over his fear of society and become someone worthy of saving the world?

Possessing a deep knowledge of mineralogy, Richard Ranashinha de Vulpian is a young and handsome British jewelry appraiser who owns a small shop in Japan. One fateful night, Seigi Nakata, a righteous college student, saves him from drunks who were harassing him due to his good looks. Upon learning of Richard's identity, Seigi hires him to appraise a pink sapphire ring that was left behind by his deceased grandmother. Before long, Seigi becomes a trusted part-timer at Richard's shop. Together, the duo solve various jewel-related requests from diverse clients of different backgrounds. Step by step, they unravel the hidden motives and feelings that lie within the gems in order to understand and empathize with the little stories behind each piece of jewelry.