Junji Ito's Cat Diary: Yon & Mu is Ito's account of his and his wife's (or fiancee's, at the start of the volume) experiences living with two cats. J-kun (Junji Ito) starts off as more of a dog person than a cat person, but A-ko (Ito's wife) loves cats and plans to bring Yon from her parents' home to her and J-kun's new house. While she's at it, she also decides to adopt Mu, a Norwegian forest cat kitten.
Initially, J-kun is terrified of Yon, who he views as having a cursed face. It doesn't help that Yon also has what appears to be a face-like pattern on his back. J-kun falls for Mu almost immediately, but Yon grows on him as he realizes that he's just a cat with a weird face.
There are the usual cat manga stories about playing with them, sleeping with them, and dealing with their quirks, but with Ito's creepy and intense art style (and his love of poop jokes). Ito often draws himself bug-eyed, overreacting to everything, and his wife is usually portrayed as a creepily smiling presence with blank white orbs for eyes. It's a weird mix of humor and horrifying moments.