Long ago, demon-like creatures known as Oni butchered humans and brought on destruction solely for their own delight. A lone man named Momotarou opposed these gruesome, near-invincible monsters, but the war against them was just beginning. Thousands of years in the future, temperamental gun enthusiast Shiki Ichinose leads a carefree life. However, after his expulsion from school, everything changes. Shiki is suddenly attacked by a man and is rescued by his adoptive father, Tsuyoshi. As the two flee, Tsuyoshi reveals that Shiki is actually a descendant of the Oni, while both he and their pursuer are from the Momotarou lineage. The two Momotarou soon clash in a fierce battle, and Tsuyoshi sacrifices himself to protect Shiki. Devastated, Shiki awakens to his Oni blood that grants him immense strength at the cost of going berserk. Although the enemy escapes, Naito Mudano, an Oni teacher at Rasetsu Academy, takes an interest in Shiki. Under Mudano's guidance, Shiki must learn to control the Oni blood—if he ever hopes to avenge his father.

A lot has happened for Nagi Umino and Erika Amano: they were swapped at birth, learned of their engagement, and have started living under the same roof. The two now share their home with Nagi's sister, Sachi, and his crush, Hiro Segawa. Despite this unusual domestic situation and frequent quarreling, the group is beginning to settle into a life together. However, the return of Nagi's childhood friend Ai Mochizuki to Japan complicates things. Ai suddenly declares her intention to marry Nagi, and although he turns her down, she is committed to having him all to herself. Now with four girls around, each with their own thoughts about him, Nagi must figure out his own feelings and the best way forward.

In the Kingdom of Ridill lives a genius magician known to be the first person to ever use chantless magic. With this amazing skill, Monica Everett joins the Seven Sages as a hero who can defeat powerful dragons, such as the legendary black dragon, all on her own. However, the truth is that the Silent Witch developed chantless magic due to being too shy—preferring to live on a mountain top, far from society. Her secluded lifestyle changes, though, when a fellow sage tasks her to covertly defend the second prince, Felix Arc Ridill, from attempts on his life. Unfortunately, that means she will have to go undercover as a student at Serendia Academy. Between guard duty and her social anxiety, Monica is facing her most difficult mission to date.

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.