Koi to wa Yobenai

From Girls' Generation Scanlations: 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 the young man and the kitten named Yakinori. With each passing day Ei becomes happier and happier. Until one day Ei's ex returns. What will Ei do with this sudden development? A love wound that is healing, drawn warmly to reflect a pure feeling. A collaboration jewel!