 If you liked
Maigo no Kemono-tachi
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 ...then you might like
Chiisana Oningyo Biyori
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The Stray Beasts and Nice Day For a Little Mermaid are both manga aimed at girls/women featuring a mermaid as the female protagonist. Though not in the usual way as you might expect from Hans Christian Andersen's The Little Mermaid, as these manga aren't really about mermaids wanting to turn into a human based on curiosity and eventual attraction (though the former does feature a romance and the MC is often seen with legs). Check either of these out for some cute-looking takes on mermaid stories.