[DeepL Translation - needs review] Introduction to Volume 1: If you succeed in having a baby with a mermaid, 100 million yen! Suddenly, some dubious men visit Makai, who is short of money anyway. They say that Mami's genes have a high chance of making a child with a legendary mermaid (penis) who is on the verge of extinction ....... They say that if she succeeds in having a child with a mermaid, they will pay her 100 million yen. Making a baby with a mermaid you don't know where she is! Bewi...
This is a silly fantasy comedy about a broke guy who somehow seems to draw in more and more mermen around him. The setup given at the beginning of the volume has our protagonist approached by some shady men (from some kind of mermaid research institute or something) who tell him that mermaids are dying out; there are basically no female mermaids left, so male mermaids have adapted to be able to lay eggs themselves, and protag is one of the lucky ones who's sperm is highly likely to fertilize said eggs. They'll give him １億円 if he can show them baby mermaids, and off begins his quest to become rich.
Despite the rather raunchy setup and the singular sex scene detailed in chapter two, volume one is otherwise firmly in the "comedy" category, to the point where I'm not entirely sure why the author decided to explicitly show the sex in the first place (well, as explicitly as you can show things with white bars covering everything, I suppose). More sex is implied later in the volume, but it's of the "cut to black" variety, with nothing actually shown. Most of the volume is rather slice-of-life, us just following the protagonist living his day-to-day life.
Overall I ended up really enjoying the volume; the protagonist is a kind guy at his core, and his relationship with his childhood friend hit some emotional beats I definitely wasn't expecting from a book like this. Little/no furigana was given, but I found it a very easy read, what with most of the conversations centering around everyday life.