Seinen magazines seems to be the place to go these days if you want quirky romance manga starring adults, much like this one.
FRIDAYS AT THE ATELIER (Kinyoubi wa Atelier de), by Sakura Hamada. First published in 2019 and first published in North America in 2024.
PLOT:
Emiko is so exhausted with her life that she's considering suicide, but then she comes across a man who has tripped in the street, spilling a bag of fish. The man is Shunsui, an artist, and he believes Emiko to be the perfect model for his work. That's how she finds herself at his studio, nude and covered in fish. It's an odd arrangement to be sure, but Emiko usually gets a free meal of freshly cooked fish out of it so that's something. The longer this goes on, the more Emiko wonders if Shunsui wants more from here than mere modeling...and if she does as well.