I remember finding this fanfic a year or so ago, before I even had an account or fully understood what Touhou was. (I was one of those "What anime is this from?" guys.) At the time, I thought that it was a modern-day au, and thought that Renko and Maribel were actually AU versions of Reimu and Marisa.
Now here I am, a few years later, gawking at the same work yet again. Except this time, I know what I'm looking at.