I'm a librarian who loves anime, manga, and reading a wide variety of genres.
So, there's a murder in this, but weirdly enough I'd say that the "mystery kittens" storyline was actually the primary one and the murder was secondary. Charlie did his best to stay out of the murder investigation as much as possible, and all of it was resolved off-page, to the point that I had a little trouble following the threads.
The kittens were cute, and that storyline was resolved in a way that was warm and fuzzy but not to a completely unbelievable degree. Although I did have trouble believing that someone who didn't initially want pets would say "sure, I'll take all five kittens." Five kittens turn into five cats, and that is a LOT to take on all at once