High school student Kaname Sudou receives an invitation from a classmate to play Darwin's Game, a mobile game he has never heard of. However, as soon as he opens the application, a green snake suddenly pops out from his phone screen and bites his neck, leaving him unconscious. Waking up in the infirmary without any signs of a snake bite, he is told by the school to take the rest of the day off. Although he is puzzled by what has happened, he dismisses the surreal experience as a hallucination and boards the train home. Unfortunately, his curiosity gets the better of him and he uses the application once again. As the application appears to be just like any other battle game, Kaname breathes out a sigh of relief and decides to start his first match. However, the pleasant surprise is short-lived, as his in-game opponent unexpectedly appears right in front of him and attempts to hunt him down with a knife. As he desperately runs for his life, Kaname puts two and two together and realizes that Darwin's Game is not an ordinary game, but rather, it's a brutal fight for survival. [Written by MAL Rewrite]

The story follows Iruma Suzuki, a 14-year-old human boy, who is sold to a demon by his parents. The demon, known as Sullivan, takes Iruma to the Demon World and officially adopts him as his grandson. He enrolls Iruma in the Babyls School for Demons where he is the headmaster and where Iruma quickly befriends the demons Alice Asmodeus and Clara Valac. However, Sullivan tells Iruma to never reveal that he is human since he will be eaten if anyone finds out. Iruma then vows to blend in during his time in the demon world, although he only stands out because of all the situations and adventures that arise.

Following the conclusion of the three-way organizational war, government bureaucrat Ango Sakaguchi recalls an event that transpired years ago, after the death of the former Port Mafia boss. Osamu Dazai, still a new recruit at the time, was tasked with investigating rumors related to a mysterious explosion that decimated part of the city years ago—and its connection to the alleged reappearance of the former boss. Due to circumstances out of his control, he is partnered with Chuuya Nakahara, the gifted yet impulsive leader of a rival clan known as the ''Sheep,'' to uncover the truth behind the case and shine a light on the myth of Arahabaki—the god of fire who might just lead Dazai to the case's solution. Meanwhile, in the present day, it is business as usual once again for the Armed Detective Agency. Their peaceful break will not last for long, however, as enemies old and new gather their strength and prepare for another face-off. [Written by MAL Rewrite]

Ichirou Kuga has suddenly found himself taking on the responsibility of caring for his two younger siblings after their father's untimely death. To make ends meet, Ichirou rents out rooms in the apartment complex he inherited and works full-time as a shoujo manga artist. However, his manga sales are low, his assistants have recently left, and deadlines are fast approaching. As stress threatens to overtake Ichirou, salvation comes in the form of an extremely competent novice artist, Shiori Goshiki, who becomes his new assistant. With her skills, they are able to tide over the difficult situation, and things begin looking up. But in a bizarre accident, a supernatural experience unfolds between Ichirou and Shirou, which leads her to declare them engaged. With this seemingly innocuous action upending his life, Ichirou now has to manage his new and peculiar relationship with the mysterious girl, all the while following his own passion and fulfilling the duties that rest on his shoulders.