manga/manhwa about human(ish) characters that are part-time animals, transformed pets, reincarnated beasts (magical or otherwise), or mysterious creatures! either a protagonist, sidekick, or love interest, they temporarily disguise themselves as, were, or become an animal that is perceived (initially or throughout) as a separate creature to their humanoid form by a protagonist, side character, or the general public.
for regular non-human supernatural pets manga protagonists have been keeping in their homes, please see my other stack!
Not on MAL:
I Was Supposed to Be Reincarnated as Fenrir, but No Matter How You Look At It, I'm a Shiba Inu by Saku & Rokusho Rokurota
'Tarou, an office worker, saves a wolf-like creature from being run over by a truck and loses his life. When he arrives in another world, a capricious goddess reincarnates him as Fenrir, the strongest holy wolf on the inside and a Shiba Inu on the outside. Taro meets Princess Sophia, who has been praying to Fenrir, believing him to be the messenger of salvation, and sets off on an adventurous journey...?!'
The Magical Cat Ghee by Daitaro NISHIHARA & Stren Japamanga
'In Durhein, known as the "Country of Beauty," magicians governed under the peaceful rule of King Al-Aktha. One day, a strange light fell from the heavens, turning all the magicians into cats. From thenceforth, magic was oppressed. No one knows why such a terrible thing happened. The world's only hope is one once known as the "Magician of the East;" now just a cat called Ghee. Ghee and his companions set out on a long, tireless journey to bring back a world filled with hope...'
Emperor's Dog by Nam Do-gyeom
'I was reincarnated into another world after an unexpected accident. Am I the emperor's daughter? Or the duke's daughter? When I opened my eyes with a pounding heart, what I saw before my eyes was a white, soft puppy's paw. Since this is how I came to be, I had to find a way to live. There was only one thing this small, insignificant puppy could do. That was... "If you just raise me, I will definitely repay the favor, Your Majesty!" "Very well, I will take you with me." "What a wonderful choice, Your Majesty. It is a choice you will never regret!" The path of a traitor who clings to those in power. That is my path! I will boil the emperor and give him a comfortable and cozy life as a puppy, and I will also find a way to become a human!'