Koi to wa Yobenai

After getting dumped by his lover on Christmas Eve, Ei finds a young man with a cat covered under the snow outside of his apartment. That's how he met Junpei. The serious Ei makes some place in his heart for this young man and a kitten named Yakinori. With each passing day, Ei becomes happier and happier. Until Ei's ex sudden return. What will Ei do with this development?