Hi!

I'm looking for a romance manga with a male lead who transforms/can turn into some sort of creature like a monster, kitsune, demon, etc. A female protagonist is preferable but it doesn't have to have one.

The only examples I can really think of are

Niehime to Kemono no ou
Abide in the Wind
Kanata Kara (This one especially)

All genres are fine I'd just like a happy ending.

Thanks!

Strange Dragon - male can turn into a dragon. It's short though.
Fruits Basket - the male lead and others can turn into animals. There are two male leads but one of them can also turn into a monster as well as an animal. They turn into animals a lot, and the one guy turns into a monster maybe once or twice throughout the manga. It's a super cute love story though.
Kamisama Kiss - Male lead is a fox demon. He doesn't really transform though. He just has fox ears and a tail. Once in the story he transforms into a fox. You might still like it though.
Hope one of these is helpful.