Shiki and the gang get through Dragonfall and arrive at the Aoi Cosmos, which is ruled by Poseidon Nero of the Oración Seis Galáctica, and land on a fire planet, Red Cave, at the suggestion of Witch. The planet is overflowing with Water Ether, and is an environment that is a far cry from a "fire planet" covered by the ocean. As the Edens Zero crew enjoy a brief vacation at the ocean, they discover a town beneath the waters...!

The Doomsday System is activated and all of Foresta is in danger.

Now that everyone's back on the ship, Shiki introduces Xenolith, who has some disturbing statements that affect Shiki and his companions. Meanwhile, Oceans 6, Poseidon Nero's group, assembles and prepares for their next move.