Reader-added tags as of now consist of "A boss who's too dangerous to antagonize" and "Manga Folk Tales of Kogasa".

So the recent series of events (depicted) are from 18 or so years ago, and the first of these 4koma came out around 10 or 11 years ago. So someone was busy long before Touhou hit it big. 2002 (roughly the timeframe of these events) is when the Embodiment of the Scarlet Devil came out. Imperishable Night a few years later seem to be when the storm hit.

One of the beginning strips showed Mizuki-san on a trip to California with Sanae around Jan 2001. I wonder about the timetable to all this.