During the late 19th century, Great Britain has become the greatest empire the world has ever known. Hidden within its success, the nation's rigid economic hierarchy dictates the value of one's life solely on status and wealth. To no surprise, the system favors the aristocracy at the top and renders it impossible for the working class to ascend the ranks. William James Moriarty, the second son of the Moriarty household, lives as a regular noble while also being a consultant for the common folk to give them a hand and solve their problems. However, deep inside him lies a desire to destroy the current structure that dominates British society and those who benefit from it. Alongside his brothers Albert and Louis, William will do anything it takes to change the filthy world he lives in—even if blood must be spilled.

Hiyori Iki is excited to start high school alongside her two middle school friends, but Delivery God Yato seems to have other plans for the day. Will Hiyori be able to make a good impression on her first day? Or will Yato cost her a happy high school life? On another day, Hiyori decides to take advantage of the beautiful weather and invites a number of people to gaze at the cherry blossoms, including the fearsome combat god, Bishamon. But how long will their blissful day last when Yato and his old rival Bishamon start to drink together?

Now branded for death and destined to be hunted by demons until the day he dies, Guts embarks on a journey to defy such a gruesome fate, as waves of beasts relentlessly pursue him. Steeling his resolve, he takes up the monstrous blade Dragonslayer and vows to exact vengeance on the one responsible, hunting down the very man he once looked up to and considered a friend. Along the way, he encounters some unlikely allies, such as a small elf named Puck, and Isidro, a young thief looking to learn swordsmanship from the former mercenary. As the ragtag group slowly comes together after having decided to join Guts in his quest, they will face incredible danger unlike anything they have ever experienced before.

In the backwater town of Bellforest lives a 14-year-old boy named Renton Thurston. He desires to leave his home behind and join the mercenary group known as Gekkostate, hoping to find some adventure to brighten up his mundane life. However, stuck between his grandfather's insistence to become a mechanic like him and the pressure of his deceased father's legacy, the only excitement Renton finds is in his pastime of riding the Trapar wave particles that are dispersed throughout the air, an activity akin to surfing. Everything changes when an unknown object crashes through Renton's garage, discovered to be a Light Finding Operation—a robot capable of riding the Trapar waves—specifically known as the Nirvash typeZERO. Its pilot is a young girl named Eureka, a member of the Gekkostate, who requests a tune-up for the Nirvash. Their meeting sparks the beginning of Renton's involvement with the Gekkostate as he takes off alongside Eureka as the co-pilot of the Nirvash.