What's Michael? by Makoto Kobayashi
Michael is a rotund tabby cat who is often likened by Americans to the comic strip character Garfield. In some stories, Michael is shown as a creature of nature, and Kobayashi expounds on the virtues of cats in the wild, often with surprising conclusions. Michael is also shown in a number of stories with different owners. It is apparent that these stories are not connected, with each one having a completely different set of supporting characters. After all, one aspect of the domesticated cat is the cat owner. The owners are occasionally more interesting than the cat.

A hard day's life - Vol.6

Ideal Cat - Vol. 9

This is a very fun and interesting series as it focuses on the cat and how he observes things around him. I've read the two above volumes and enjoyed both. Nice to have a japanese series that isn't all fighting.