My Bride is a Mermaid (my version)

My Bride Is A Mermaid is an anime television show that tells the story of a young boy named Nagasumi who is saved from drowning on his summer vacation. His rescuer turns out to be a mermaid named Sun Seto, who lives by the mermaid rules. Suns family is the head of the mermaid mafia group, and to save both of their lives, they decide that instead, the two are to be married, a decision that Suns father Gozaburo isnt happy about. Nagasumi suddenly finds himself part of a very strange union that he has some trouble adjusting to as a result of Gozaburos attempts to kill him and the interference of some other unsavory characters. Unlike his parents, Nagasumi do not possesses great inner strength and mental clarity, and he accepts the responsibilities that come with marrying Sun and gradually develops true feelings for her. Although it is usually Sun who uses her powers to protect Nagasumi, he his able to protect her in his own ways when she is threatened as well. Sun is in love with Nagasumi but cannot maintain her human form until she becomes an adult. Until then, Sun and Nagasumi must protect each other from the challenges they face if they want to live to realize their true love.

Michishio family
Nagasumi Michishio: Nagasumi is a minor character of the story. Nagasumi is likely the only one in his family who don't have a clear head, apart from his grandmother. When push comes to shove, Nagasumi demonstrates a great deal of inner strength, and even has a "danger alert" mode, where the ahoge strand of hair on top of his head perks up and he exhibits the near-superhuman ability to dodge and evade practically anything or anyone that approaches him with ill intent. He decided to face his fears and take on the responsibility of taking care of Sun as his wife, although it doesn't make it easy on him due to almost everyone in the Seto group (except Sun's mother—Ren, and Masa) who are against their union. As the series progresses, however, he truly falls in love with Sun. Sun often uses her Song of Heroes to power Nagasumi up in battle situations, but in the case where Sun is directly threatened he is able to activate the power-up by himself.

Nagasumi's father: Nagasumi's father is always shown as an object of suffering, due to his wife's dying love for him. Whenever his wife shows her interest in Masa, he is shown in a depressed state, like the time she offers Masa her home cooked meal, he is shown coughing on a burger and then subsequently harangued by his boss to get back to work.

Nagsuimi's mother: Nagasumi's mother is the easy going type, and has an interest for Masa, which her husband is not particularly happy about. Current events in her life have caused her love towards her husband to gradually die out.

Seto family
Sun Seto: The main character of the story. Sun is the daughter of the 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, Sun is unable to completely maintain her human form, and her legs revert to a tail whenever she comes into contact with water. She has gills all around her neck, tail and lungs.

Gozavuro: Gōzaburō is the boss of the Seto Group. He dotes on his daughter and hates Nagasumi for, as he sees it, trying to steal her away. By pulling strings at the ministry of education, Gōzaburō, together with many of the Seto Group members, enrolls in the staff of Nagasumi's junior-high school in order to watch over Sun, thus becoming Nagasumi and Sun's homeroom teacher.

Ren Seto: Ren is Sun's mother. She likes to encourage Sun and Nagasumi. The most feared member of the Seto Group she usually tries to keep her husband and any other Seto Group members in check. Ren on appearance is seen as a kind and gentle person but shows behavior much like a yakuza member. In her human form, she worked at the swining teacther for her daughter's class. She can turn into her mermaid form and swin at fast speed. Her gills is all around her tail, neck and lungs.

Seto family's Helpers
Maki: Maki, despite being only few inches tall, is an assassin working for the Seto Group, as well a devoted friend of Sun. She uses a shell to shoot water balls as fast and powerful bullets and has a seemingly unlimited supply of ammunition. She, like Gōzaburō, dislikes the idea of "losing" Sun to Nagasumi, and will often distract Sun with sweet talk in order to fire her shell gun at Nagasumi. She thinks that Nagasumi and Lunar would be a much better match.

Others
Lunar: Lunar is a childhood friend of Sun. She has used the powers of her mermaid form to become a swinmer She initially thought that Sun was boasting Nagasumi to her, and in an attempt to outdo Sun she decides to steal him away from her by making Nagasumi her servant, since Nagasumi has also seen her mermaid form. She decides Nagasumi's house until his servant status is over. Like all girl mermaids, she has gills on her neck, tail and lungs.

Akeno Shiranui: Akeno is not only a mermaid but also a "mermaid examiner". She has the responsibility of deporting all the mer-people who fail to qualify as not only resembling humans but also not arousing any suspicion of their true identities; and unlike the other mermaids in the cast, apat from Lunar and Ren, Akeno is capable of suppressing her mermaid transformation, for brief moments, after coming into contact with water, having trained herself to do so. She has gills on her neck, lungs, and tail.