Hiroshi Ibuki is a geologist and deep-sea archaeologist participating in a deep-sea drilling operation. This mission targets the ocean floor, seeking clues to Earth's primordial origins, with Hiroshi focused on geological research related to planet formation. During deep-sea excavations for these ancient secrets, he accidentally discovers a previously unknown colony of luminescent bacteria. This bacteria emits light reminiscent of the Aurora Borealis.

Unearthed and revived, the bacteria display aggressive adaptive behavior. Rather than adjusting to the modern environment, they initiate a process to transform Earth's conditions back to their ancient habitat. This reversion to an early primal state would render the planet incompatible with current life, posing an existential threat. Following this discovery, Hiroshi becomes part of the team working to understand and counter the bacteria's global impact. The narrative centers on his direct involvement, from the initial deep-sea excavation through the scientific and operational challenges triggered by the bacteria's adaptation.

His scientific expertise places him at the center of these unfolding events. The story documents his role throughout the crisis.