Looking for a hentai manga series that was once on Fakku

This was before Fakku transformed to being almost exclusively paid subscription content. I'm not sure if this series is on Fakku anymore. I read it probably around 2013-2015, though I loved exploring Fakku deeper, so it may be from before that even. I remember it was a series, and had quite a few chapters, probably 11 or even more. Pretty sure the characters were original, i.e. not doujin. The setting eludes me, but I think most of the characters knew each other through work - some sort of business, maybe manga publishing. Female character with long dark hair was very popular and I remember the comment section being mostly praise for her. The one scene I recall clearly is her eavesdropping on a guy having sex with another girl and masturbating to it. That other girl said something about this long dark haired girl, and called her old (oba-san or something), to her chagrin, and she commented she isn't even thirty.

If anyone can help me hunt this down, much appreciated. It's been driving me crazy.

Still looking for this