Early 2000s Tokyo. Isobe, a combatant for the evil corporation Ganglion, spends his days on the battlefield. Whether it's the "Tokyo Cedar Pollen Operation" or the "Mount Fuji Demolition Plan," he faces off in nothing but a bodysuit, only to be crushed by the hero Hopeman time and again. As he struggles under unreasonable bosses during the dawn of compliance, his story unfolds—a workplace drama dedicated to all who work, following the bittersweet life of a salaryman soldier.

Ren Homura has just moved back to his hometown of Kaminohara, but he is not able to remember much about the time he spent there other than vague flashbacks. When he retrieves his cell phone which he had sent to a shop for repairs, he finds that a mysterious game titled "Monster Strike" has been installed on it. Unaware of its purpose or how it got there, Ren decides to open it, an action that will change his life forever as he finds himself suddenly attacked by a strange man. Now trapped on the roof of his school which strangely has been designated as a "stage," Ren is shocked to see the man summon a realistic monster from the game, one that is more than capable of inflicting damage on a human. His only chance of getting out of this situation alive is by summoning the dragon Oragon, who tells Ren that he will crush the opposing monster for him. Unfortunately, it turns out that Oragon is a tiny dragon that is completely useless!

Lunia, the daughter of the Count of Persephone, was shunned by her father and treated like a tool by her half-brother, leading a lonely life. Meanwhile, she is chosen by a priest to be engaged to Hades, the head of the Duke of Khronoa family, and decides to marry into the cursed duke family. The Duke of Khronoa, feared as the "King of the Underworld," is cursed with a short lifespan if he does not marry a bride chosen by the emperor. However, Hades tells Lunia that he has no intention of loving her. In order to keep Hades alive, Lunia deceived him and spent the night with him, then disappeared without realizing that she was pregnant with his child. Seven years later, Hades somehow managed to find Lunia and tried to take her back with the child...

Third season of . The gods of the world—from Greek to Norse to Hindu mythology—gather every one thousand years to make one important decision: whether or not to wipe out mankind. Repulsed by humanity's selfishness, the council unanimously votes to destroy all humans. But before the decree is enacted, Brunhilde, one of the 13 Valkyries of Valhalla, interrupts the meeting to give mankind a chance at survival. Brunhilde proposes the idea of enacting Ragnarök, an event in which the strongest 13 mortal warriors fight against 13 gods in one-on-one matches. Although the trial is ridiculed by the gods, the demigod takes advantage of their pride and forces them into an agreement. However, Brunhilde herself must recruit the mightiest heroes throughout humanity's thousand-year history and guide them to victory before they meet their untimely demise.