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.

Denji is robbed of a normal teenage life, left with nothing but his deadbeat father's overwhelming debt. His only companion is his pet, the chainsaw devil Pochita, with whom he slays devils for money that inevitably ends up in the yakuza's pockets. All Denji can do is dream of a good, simple life: one with delicious food and a beautiful girlfriend by his side. But an act of greedy betrayal by the yakuza leads to Denji's brutal, untimely death, crushing all hope of him ever achieving happiness. Remarkably, an old contract allows Pochita to merge with the deceased Denji and bestow devil powers on him, changing him into a hybrid able to transform his body parts into chainsaws. Because Denji's new abilities pose a significant risk to society, the Public Safety Bureau's elite devil hunter Makima takes him in, letting him live as long as he obeys her command. Guided by the promise of a content life alongside an attractive woman, Denji devotes everything and fights with all his might to make his naive dreams a reality.

Before Chise became the "ultimate weapon," there was another—Lieutenant Mizuki. A battle-hardened military woman, she volunteered for an experimental procedure after injuries left her unable to return to the battlefield. As the prototype ultimate weapon, Lieutenant Mizuki was highly successful on the battlefield, however, as the first candidate, her development was limited. When a more suitable candidate to become the weapon, Chise, is forced into the military, Lieutenant Mizuki thinks that she is silly, weak, and unsuited for the role. As the only other person to have undergone the procedure, however, Lieutenant Mizuki can hear Chise's thoughts and is the only one who understands her. As the war rages on and Chise's development progresses, Lieutenant Mizuki discovers more about Chise, ultimate weapons, and herself.

In the Andromeda galaxy there's a planet of a highly developed human civilisation. The gentle Prince Itaka and another kingdom's beautiful Princess Lilia are about to enter a love-marriage and take over the throne, when they discover a strange object on the nightsky. Later it lands on the planet, and an alien, mechanic civilization invades King Itaka's peaceful country making nearly everybody their slave. On a fateful night Queen Lilia gives birth to twins, and to avoid misfortune, the nanny Tarama takes one of the babies away, and entrusts it to the gladiator Balga. They still don't know, that the children were born with strong powers, and hold the key to the fight against the enemy that's searching to destroy every human civilisation on the planet...