I'm a rookie comicker so please take my comments with a grain of salt, but here goes.
I really like what you have so far! I like the format and I like the humour. My favorite is the Zelda 2 reference (I am Error). It brings back memories XD
I like the art, it's simple and very appropriate to the subject. My one complain would be the fact it switches back and forth between color and black and white. I'm not sure if there's a reason for it or if it's just a schedule issue, but I would decide on either style and stick with it. Or make a different section for black and white comics (see CAD's [url="http://www.cad-comic.com/sillies/"]"Sillies"[/url]).
The backgrounds are simple, but that's also usually appropriate for the style of your comic. I say usually because in #26 (Kittens, Please!), the two middle frames look a bit bare in my opinion. I think they would have benefited from having a very simple background made of building silhouettes (no need for details, just silhouettes). This would have situated the comic a bit - right now it looks like the pet shop is in the middle of a sea of concrete
My last comment is on Mikumi's hat. I really like the idea of the two "eyes" changing shape according to his emotions (or the hat's emotions). I think you should expand on that
Maybe have them grow when he's surprised or shocked, making "sad eyes" and closing in into arched slits when he's happy or laughing.
That's it from me, sorry it grew longer than I meant it to
I look forward to reading more - your comic looks very solid so far!