Cardcaptor Sakura: Kero-chan ni Omakase!

Both are special short anime, Clamp Arts, and Kero-Spinel similiar with Sumomo-Kotoko in Chibits..  

Both are incredibly high-octane short films tied to a movie, starring animal-like creatures doing all sorts of hijinks. 

Both nicely animated side adventures staring the animal companions of their respective shows. The the MCs are just cameos in the background while you get a glimpse of the crazy shenanigans they got up to when the human characters weren't there. I regularly think back on both of these for how plain fun and enjoyable they are. Not to mention both shorts were also made as tie-ins to watch with a feature length film.  

About someone that has to do something and will literally do anything for it. Both are hilarious. 

Both are small comical spin-offs of their respective series.