There is a crybaby uke and he really loved his dog, but the dog died (I think in an accident). The next day he wake up and there is a guy who claims that he is the dead dog and he turned into human, because he loves his owner. And the uke belives him, they happily live together, but one day SPOILER somehow it turned out that the seme is not the dead dog, just a school boy, who fell in love with the uke. And he lied to the uke to get closer to him. SPOILER END.

I thought it was Kamon Saeko's manga, and there is a similar dog story, but it isn't what I looking for.

It's Tonari ni Kimi no Nukumori wo.

Yes!! Thank you! 😀 😀