Like many hardworking members of the workforce, Kuroto Nakano is perpetually stressed out by his job. Still, since he lives alone, he must carry on to sustain himself. Little do humans like Kuroto know, this stress takes the form of darkness residing within a person's body and will bring one's life to ruin. Fox deities can see this darkness and have the duty to save people before it is too late. To help rid Kuroto of his stress, Senko-san, an eight hundred-year-old foxgirl, volunteers to take care of him, and will do everything she can to ease the tension in his weary soul.

Mahiru Shirota firmly believes that simple is best and troublesome things should be avoided at all costs. It is troublesome to do nothing and regret it later—and this ideology has led the 15-year-old to pick up a stray cat on his way home from school. As he affectionately names the feline Kuro, little does he know that this chance meeting will spark an extraordinary change in his everyday life. One day, Mahiru returns home to find something quite strange: a mysterious young man he has never seen before. His subsequent panic results in the uninvited guest being exposed to sunlight and—much to Mahiru's shock—transforming into Kuro! Upon revealing himself as a mere lazy shut-in vampire, Kuro promises to leave once night falls. However, one disaster after another leads to Mahiru accidentally forming a contract with his new freeloader, dragging him into a life-threatening battle of supernatural servants and bloodthirsty beings that is anything but simple.

Seven Knights Revolution: Eiyuu no Keishousha is set in a world where eons ago valiant heroes fought against the forces of Destruction. While their deeds passed into legend, the power of these heroes was later inherited by successors who fought to protect the world. One day, Faria, a successor of the Seven Knights, saves an ordinary boy named Nemo from the forces of Destruction. During the ensuing battle, Nemo summons the power of a hero and becomes a successor as well. However, Nemo's hero is a stranger that is unknown to history, and so an epic journey where the past and present collide begins. (Source: Crunchyroll, edited)

During his summer vacation, middle school student Nagasumi Michishio travels to the Seto Inland Sea. One day, while swimming at Mio Sun Beach, his leg suddenly cramps. No one is close enough to notice his desperate screams for help, and so he sinks into the ocean, where he is left to drown alone. Just as he loses consciousness, however, a mermaid appears and saves his life. That night, Nagasumi is visited by his savior, a girl who introduces herself as Sun Seto—a mermaid from a yakuza family. As it turns out, under mermaid law, a mermaid whose identity is revealed to a human must be punished by execution. To avoid this harrowing outcome, the Seto family propose a solution: Nagasumi must marry Sun or die at the hands of Gouzaburou, Sun's father and boss of the Seto clan. Faced with no other option, Nagasumi takes her hand in marriage. Now, the newlyweds face the difficult task of keeping their relationship secret. Between Gouzaburou's unending attempts on Nagasumi's life and the eccentric antics of a slew of antagonists, a genuine and innocent love blossoms between the pair as they adapt to their new life.