Fujoshi Kanojo. (2007)

Blurb:
All penniless college student Taiga Mutou wants is a cool job and a cute older woman as a girlfriend. So when he spies a Help Wanted sign outside an office and a hot girl inside, he applies for the job, no questions asked. After a few bumps at the beginning, things start going Taiga’s way, prompting him to steel his courage and ask out Yuiko, that hot girl he spied through the window, on a date. And when she later asks him if it’s okay that she’s a fujoshi (a very, shall we say, distinct kind of comics/animation geek), he tells her it’s fine out of sheer excitement. But poor Taiga has no idea how much trouble he’s just gotten himself into!

Source: www.anisearch.com/manga/4550