After an accident sent her family to their deaths in the ocean, Hinako Yaotose keeps returning to the thought of sinking forever into the sea herself. With Miko Yashiro as her only friend, Hinako manages to keep up a semi-happy facade, but whenever Miko leaves her side, she slips into despair. Everything changes one summer when she meets a mysterious girl with eyes as deep and clear as the sea, drawing Hinako in like nothing else has in a long time. During her absent-minded search for the girl, Hinako is suddenly pulled underwater by a beastly deep-sea creature, only to awaken to the presence of the girl—Shiori Oumi—who takes on a monstrous form and kills Hinako's attacker. Despite this heroic act, Shiori's intentions are no different from any other monster's: she wants to eat Hinako. The following morning, Shiori walks into Hinako's class as a transfer student, and Hinako cannot help but smile—at last, someone who could fulfill her quiet wish for death has appeared before her.

Jun Shirasaki and the Jinguuji sisters are childhood friends and neighbors. When Jun's first girlfriend, the older sister Rumi, breaks up with him, she says something that complicates the three people's relationship, their first loves, and their romance—? (Source: MAL News)

In a world of constant war between humans and witches, there exist the beastfallen—cursed humans born with the appearance and strength of an animal. Their physical prowess and bestial nature cause them to be feared and shunned by both humans and witches. As a result, many beastfallen become sellswords, making their living through hunting witches. Despite the enmity between the races, a lighthearted witch named Zero enlists a beastfallen whom she refers to as Mercenary to act as her protector. He travels with Zero and Albus, a young magician, on their search for the Grimoire of Zero: a powerful spell book that could be extremely dangerous in the wrong hands. During their journey, his inner kindness is revealed as he starts to show compassion and sympathy towards humans and witches alike, and the unlikely companions grow together.

With the completion of the Summer Troupe's show, Izumi Tachibana must now recruit five members for the next sub-troupe, the Autumn Troupe. Luckily, enough people arrive at the audition: Banri Settsu, a talented but boastful jack of all trades; Juuza Hyoudou, a stone-faced delinquent passionate about acting; Taichi Nanao, a man wanting to impress girls through the stage; Omi Fushimi, a college student, amateur photographer, and adept cook; and Sakyou Furuichi, a yakuza member who shares a past connection with the Mankai Company. But between the non-existent teamwork and multiple threats jeopardizing the show's success, Izumi realizes that the troupe might be more difficult to handle than she first thought. How will she be able to unite them in time for their debut performance?