Minamo searches for a pair of antique Sous-Marin sunglasses as a gift to congratulate Haru on becoming an official investigator. During the search, Minamo and Sota have a run-in with champion fighter Iron Schwartz.

Minamo meets Amy, a girl who has just received cybernetic eyes to cure her blindness, but learns that Amy is struggling to adjust to being able to see. Meanwhile, Haru is asked to investigate the disappearance of a highly sought-after artist in the Metal.

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.

At the jungle island, Haru realized that he can learn to walk again, and he begins to practice in secret to avoid jeopardizing his job as a Metal diver. Meanwhile, Minamo gets tested for suitability to receive a cyberbrain.