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.

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.

Holon collapses, and the others attempt to complete their investigation without her help.

After the spread of weather particles, drastic weather changes occur across the planet, and the burning sea phenomenon returns. Haru decides to use the experimental deep dive suit in an attempt to make contact with Kushima.