Dr. Thelbert holds an affiliation with the ocean city construction project central to the narrative. This large-scale development within marine environments generates significant pollution through the massive pouring of concrete into the sea, an ecological disruption sparking conflict between land-based humans and the sea people.

The character emerges during a sudden explosion at the ocean city construction site, the workplace of protagonist Hiroshi Umino. Following this incident, designer Nami Shimaoka becomes the prime suspect. Nami is subsequently revealed as an agent of the sea people, actively working to sabotage the ocean city initiative.