After the murder of their parents, 11-year-old twin brothers Thor and Rai Klein are sent away from their home planet. They find themselves awakening on the terraformed planet of Chimaera, where carnivorous plants dominate and the few humans who live there are divided into four groups known as "Rings." Soon after, they meet a young man by the name of Zagi, and the twins learn that only the "Jyu Oh Sei"—the one who conquers these four Rings—is allowed to leave the planet. Driven by the desire to return home and discover the truth behind the death of his parents, Thor resolves to survive in the harsh, merciless environment of Chimaera. However, he quickly learns there is more than meets the eye in this strange ecosystem. As Thor is swept up in the politics that entangle the Rings, he uncovers more about his parents' murder, and ultimately, humanity's fate as a whole. [Written by MAL Rewrite]

The world is in the midst of the industrial revolution when horrific creatures emerge from a mysterious virus, ripping through the flesh of humans to sate their never-ending appetite. The only way to kill these beings, known as "Kabane," is by destroying their steel-coated hearts. However, if bitten by one of these monsters, the victim is doomed to a fate worse than death, as the fallen rise once more to join the ranks of their fellow undead. Only the most fortified of civilizations have survived this turmoil, as is the case with the island of Hinomoto, where mankind has created a massive wall to protect themselves from the endless hordes of Kabane. The only way into these giant fortresses is via heavily-armored trains, which are serviced and built by young men such as Ikoma. Having created a deadly weapon that he believes will easily pierce through the hearts of Kabane, Ikoma eagerly awaits the day when he will be able to fight using his new invention. Little does he know, however, that his chance will come much sooner than he expected... [Written by MAL Rewrite]

Kyouhei, after moving away to Tokyo from his old town to get away from the events that happened, is on a goukon with his friends, including his old neighbor, Shiba. After drinking for a whole night, he and Shiba discover a dead, bloody body in the elevator. He is told by his younger sister, Utao with her Kamisama Doll, that Aki, an old friend, and his Doll are the culprits responsible.

With the seas under constant threat from the hostile "Abyssal Fleet," a specialized naval base is established to counter them. Rather than standard naval weaponry, however, the base is armed with "Kanmusu"—girls who harbor the spirits of Japanese warships—possessing the ability to don weaponized gear that allows them to harness the powerful souls within themselves. Fubuki, a young Destroyer-type Kanmusu, joins the base as a new recruit; unfortunately for her, despite her inexperience and timid nature, she is assigned to the famous Third Torpedo Squadron and quickly thrust into the heat of battle. When she is rescued from near annihilation, the rookie warship resolves to become as strong as the one who saved her. [Written by MAL Rewrite]