Similar scheme : the protagonist meet a kemonomimi girl who suddenly decide to pass most of her time in his house. In Sewayaki Kitsune ni Senko-san, she's even here the whole time.
The girl is very attached to the protagonist. In one, she's a fox, and in the other, she's a cat. She's sometimes clueless about things that humans like or do.
Their relationship is also similar, as one takes care of the other. But in this case, it's inverted : in one, it's the protagonist who takes care of the girl while on the other one it's the girl who decide to act like his wife or his mother. read more
Both are featuring an animal girl and are light-hearted slice of life comedies. However, while in Come Come Vanilla the main character is a high-school boy, the protagonist in Wanko Number One is an already working man.