The First Love of the Sushi Restaurant Owner is a Mermaid
Samezoku e no sasagemono
Kind of like an omegaverse, but only because the uke is from a clan where they can become female depending on some conditions (like winning or losing a fight at their ceremony of coming of age). Whereas the seme is from another clan where they are beastmen descendants from a human and a shark's child. And the ones with the most (powerful?) shark blood can even transform their lower body into shark mode. Reminds me of Umi no Soko of course.
Spring Amidst My Wintertide
"I mean, in general it was kinda weird but acceptable. Then he turned into a wolf while having sex. That left me speechless and disgusted." I was also VERY surprised. Other than that, I kinda liked him and the FL was not too bad either. Bonus point : the Ml had big boobs and big nipples + a window boobs.
Pheromoholic