San Seto

San is the daughter of the Yakuza Seto Group's boss, Gōzaburō Seto. She is a firm believer in the chivalrous spirit of mermaids, and is devoted to her role as Nagasumi's wife. She is also in love with Nagasumi. Since she has yet to become an adult, San is unable to completely maintain her human form, and her legs revert to a tail whenever she comes into contact with water. She often cites the similarity between the Japanese words "ninkyō" (任侠, "ninkyō"? chivalry) and "ningyo" (人魚, "ningyo"? mermaid) to stress her adherence to honorable courses of action. It is later revealed during Lunar and Nagasumi's wedding that if the need arises she can fight very well with a sword and also shows behavior much like a Yakuza member. Her name is related to Seto Inland Sea and is a direct reference to the Sun.