After his high school graduation, Yuuki Wakura realizes it has been five years since his sister's disappearance during a "Mato disaster." Throughout Japan, mysterious entrances have opened to a dimension called "Mato"—a demonic metropolis filled with disastrous monsters known as the "Shuuki" that threaten the safety of humans. However, a new hope arose, as the discovery of a Mato fruit that grants supernatural abilities exclusively to women allowed them to fight against the Shuuki. Due to this, a new matriarchal government was formed, establishing a female organization called the Anti-Demon Corps, which caused men to fall to the bottom of society. When Yuuki suddenly finds himself in Mato, he is unable to escape on his own. But just as he anticipates a gruesome end by the Shuuki, a girl in a militia outfit appears and protects him. As the chief of the Seventh Unit of the Anti-Demon Corps, Kyouka Uzen is ambitious yet devalued by her own peers due to her power being deemed unusual. Now in a life-or-death situation, Kyouka takes the opportunity to find out the true potential of her superpower by using Yuuki: in order to defeat the Shuuki, he has to become her slave.

Shuuichi Kagaya is what one would consider an average high school student, but sometimes, he turns into a monster. He doesn't know how or why he got his abilities, only that he would prefer no one knows about them. One night, he finds a building ablaze with a girl trapped inside. Deciding to save her, he transforms and carries her to safety, but accidentally drops his phone. The next day, the girl he saved—Claire Aoki—finds him and confronts him about his monster identity. She even goes so far as to push him off the school roof to prove her theory after Shuuichi denies her allegations. Desperate to save himself, he transforms, and Claire snaps a picture in order to blackmail him into telling her everything he knows about monsters, which, ironically, isn't much. As it turns out, Claire has a secret of her own: she has been searching for her sister, who also became a monster. She enlists Shuuichi's help to track her down, but they aren't the only ones searching for answers. [Written by MAL Rewrite]

A man with a passion for vending machines awakens to realize that he has not only died, but he has also been reborn as one of his beloved machines! Although he is a modern appliance in a fantasy world, he requires money in order to keep functioning. He is stuck in one location until a young girl named Lammis stumbles upon him. Amazed by the drinks and food he sells, Lammis uses her "Blessing of Might" to lift him with ease and take him back to the village of Clearflow Lake. There, she officially dubs him Boxxo. Despite his inability to converse with the villagers, Boxxo becomes an essential part of the community. His goods provide nourishment, and, as he gains new abilities and products, he becomes a staple of daily life. Nobody is as loyal to Boxxo as his first and best customer, Lammis. The more time he spends with her, the more he tries to help her elevate her skills as a young hunter.

The "Noblesse" Cadis Etrama di Raizel, also known as "Rai," is enrolled in Ye Ran High School by his servant Frankenstein to stay hidden from the sights of the Union, a mysterious organization out for Rai's blood. Rai commences his life as a student, making himself familiar with his classmates and the daily activities of humans. However, his new life is far from peaceful, and Rai is soon forced to save his new friends from the hands of the Union that had abducted them. Meanwhile, M-21—a Union agent gone rogue during Rai's rescue operation—joins the Ye Ran High School security staff after a proposition by the school's director, who happens to be none other than Frankenstein himself. On the surface, M-21 is a prim and proper employee, but in truth he is shackled by his former ties to the Union and the inevitable consequences of betraying the organization. To further complicate matters, Nobles Regis K. Landegre and Seira J. Loyard enroll in the same school to investigate the Noblesse. While the Union conducts a manhunt for M-21 to extract clues regarding their missing agents, Rai is forced to keep his identity hidden while protecting all that he holds dear. [Written by MAL Rewrite]