Well not really the doujin, but the extra the author drew where he/she described that Mamizou was like a tired OL(Office Lady) And I'm really only asking this because I can't remember the doujin and it's bugging the hell out of me T_T

You might get a better response from the pinned post for finding manga. It's likely to get lost in the shuffle otherwise.

Personally, I don't recognize it from the description, but someone else probably will.

Ah thanks, sorry i didn't know and this thought has been bugging me for a while already XD