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...

Seventeen-year-old Marco Polo leaves his home in Venice on a trip to the little-known country of "Yuan", in the company of his father Nicolo and his uncle Matteo. Their mission is to deliver the sacred oil from the Tomb of Christ and a letter from the Pope to the Kublai.