The irony of this is that I'm only still reading because of Karen...whose stupidity might just surpass the MC's. Great figure, lovely hairstyle (uncommon among female characters in general; the only style I've seen like it is that of Tsukioka Kogane of Idolmaster--and she has a similarly fine figure)...and, most remarkably, she's an OL that wears thighhighs instead of pantyhose. Almost miraculous, that.
The greenhair's little sister is right--the MC is very much a good-for-nothing, but at least Karen has her looks.