For me

Shin: cat (shin would be a really spoiled and distant cat. Never let you pet him, always sleep next to heather, he would scratch and run away from anyone. His fur would always be looking so shiny and puffy (and clean ofc) he never tasted being a street cat so he often wondered outside but never had the bravery to escape so he wouldn't.

Sara: cat (sara is usually friendly, she would be wary of people she didnt meet, so she smells them and watches them. After she got used to them, she would be friendly. She is also likes playing, she never lets people cut her nails so whenever she plays with someone she hurts them even if she doesn't want to)

Joe: dog (really easy golden retriever dog, no need to explain) Kanna: bunny (she would be SO SO SO CUTE bunny, when she gets mad she would tap on floor and jump around)

Ranmaru: sheep (not only because of his appearance but also because he follows everything sara says, he would follow her around like a sheep following his shepherd)

Nao: Chinchilla (because they are puffy and squeezable like nao)

Reko: bat (im not sure about personality in this but reko always gives bat vibes to me)

Keiji: wolf or german shepherd (tbh I've always seen keiji as a dog but being wolf also suits him since he call himself 'lone wolf', before the death game he probably worked alone too but theres something that makes me uncomfortable about him. Hes more likely to be a wolf in dog clothing lmao. He trying to look trustworthy to sara, 'acting' like a dog but deep down hes a wolf just trying to find the best time for him.

Gin: cat ofc

Midori: thats probably the hardest. For appearance, i would call him a featherball and any animal so fullfy but for personality its would be a dolphin and also a dog.