S01E21 — Godai's Panic! The Cat Who Came to Ikkoku.

Godai and Sakamoto go out drinking with friends and Sakamoto gets Godai completely drunk. While he's in his druken stupor Sakamoto asks Godai to take care of his new pet cat while he goes out of town, and when Godai learns its name is Kyoko he happily agrees. The next morning, Godai wakes up in Sakamoto's apartment and doesn't remember a thing. After some convincing, Godai reluctantly agrees to take care of Sakamoto's cat, but is worried because he thinks Ikkoku has a no-pets policy. He manages to sneak the kitten into Maison Ikkoku, but his troubles begin right away when the cat uses the bathroom on his futon. As he screams her name in anger, the manager runs to his room to see why he was calling her. Before long the other tenants find out about Kyoko-chan. The kitten and Godai quickly bond and the other tenants manage to keep it a secret from the Manager while its staying with Godai, but once the cat goes missing Kyoko finds out and has to help him find her.