She is Nagasumi's young-looking mother. She moons over Masa all the time and enjoys ignoring her husband. She approves of Nagasumi and Sun's relationship. 

Michishio Nagasumi's life couldn't be any more normal. In an odd twist of events, during his summer vacation he ends up almost drowning in the sea. Luckily, the cute mermaid Seto San appears to save him. However, San is from a yakuza mermaid family and according to their law, if a human is to catch sight of a mermaid, either he or the mermaid must die. The only other way is for Nagasumi to be taken in as a family member, marrying San. In attempts to save both of their lives, Nagasumi asks for San's hand in marriage. Nagasumi's summer vacation reaped more then what he would expect, as he must now protect San from others finding her secret out. 

A young boy gets saved from drowning by a mermaid but, according to mermaid law, if a human sees a mermaid's true form, both have to be killed. The only solution to the problem is for him to marry her. But can they keep her secret from being found out? <br><bR>(Source: Animewaves)

An exclusive picture drama released with the Blu-Ray Box Set of Seto no Hanayome. The first part starts out with gags and the characters drawn in a simplistic chibi style. It's followed by a quick recap and then goes into the main picture drama story.<br>
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(Source: Kitsu).

Mother Michishio