Neko wo Hirotta Hanashi.

Igai picked up what he thought was a sick abandoned kitten on the way home from work. But it rapidly grew into a monstrous single-eyed furry thing. If anyone finds out they'll surely both be killed? But the secret life between Neko and Igai is surprisingly cute and interesting. The popular Twitter comic finally collected for publication!

(Source: Kodansha, translated)