The small amount of story included in the other 5% is about a guy working at a health clinic's pool where he does everything from stare at women to have sex with them (and possibly teach them how to swim but that's never actually shown). His boss is a pink haired girl who appears to be about the same age as him. She's your typical tsundere who likes the guy despite his perverted tendencies but can't tell him how she really feels. Most of the first half of the episode is full of sex scenes between the protagonist and a patron of the clinic who can't swim. She is a sexually deprived housewife and makes a move on the guy right away. The second half has a shorter scene between the protagonist and the tsundere girl.
While none of the sex scenes are all that bad, they're simply average. They're directly back to back and eventually they serve their purpose, but each individually is kind of slow and none of them have anything unique from scenes in most hentai. Most of the animation is repetitive and has shots from strange angles. Also in this, when the girls cum, they cum like a sprinkler which makes a twinkling noise every time. The voice actresses do sound good, and they get better and better as the hentai goes on.
A normal vanilla hentai catering to swimsuit and MILF fetishes, Shiofuki Mermaid is enjoyable enough but leaves a lot to be desired. The poor repetitive animation and lack of anything unique really keep it from being very good.
