Construction of an artificial island is disrupted by an unexplained phenomenon known as "burning sea". Masamichi Haru is injured by burning sea during a test of early Meta-Real technology, leaving him comatose for fifty years. Now elderly and wheelchair-bound, he still hopes to solve the mystery of burning sea. His friend Eichiro Kushima now hopes to use the Meta-Real, also known as the Metal, to research the burning sea phenomenon.

Haru reminisces about his youth, from his parents' struggles with poverty that led to trouble with the yakuza, to his meeting a dolphin that inspired his fascination with the sea, and finally to his exploration of the ruins of his city, now underwater because of climate change, which led him to become a test diver for early Meta-Real experiments.

Haru makes contact with Eliza and receives Kushima's proof that the weather particles will cause worldwide disaster. Haru broadcasts the proof on the Metal, and the world's leaders quickly agree to shut down the Metal to kill the weather particle nanomachines. Kushima's consciousness then contacts Haru and explains that the ocean itself will replace the functionality of Metal via the salt water in the human body. Haru, restored to his younger self, is safely returned to the surface, where he reunites with Minamo.