Seto Gouzaburou is the excessively protective and loving father of Seto Sun. As the head of the mermaid Yakuza in the Seto region, Gouzaburou is fierce and formidable.
He despises Nagasumi and consistently attempts to have Nagasumi killed throughout the series, deriving great pleasure from fantasizing about Nagasumi's demise.
Serving as the form teacher for both Sun and Nagasumi, Gouzaburou keeps a watchful eye on Sun during school hours. However, over time, he begins to appreciate his role and may even develop a genuine concern for his students.
