Asobi ni Iku yo!, Nyan Koi! Recommendations
both involve a regular guy getting pulled into a cat world
the main guy also has a childhood friend that likes them
they both have a decent amount of comedy in it
and there both harems so they have those generic episodes like the pool/beach one and the onsen/hot-tub one.
Both Harem/Neko theme. Asobi ni iku yo! focuses on the action scenes, Nyan Koi is more about comedy and slice of life; however, both are a must-watch for cat/harem lovers.
I decided to compare Asobi ni Iku yo! to Nyan Koi! solely because they both involve cats. Well technically Asobi involves alien-cat girls, while Nyan Koi! simply involves cats and some dude that can talk to them. However, they both are romance-comedies, ecchi, and harem anime's.