Moriya Shrine | Source for all things Touhou

And it seems that 온동환 has a huge amount of child attendees just like Reitaisai, since they've been hosting it at a large playground park called 독골어린이공원 since last year. They have a strict policy on suggestive merch and ban any skimpy cosplays. (The fact that they hosted it on playground from the very start must've meant that the organizers saw large amounts of schoolgirls on past Touhou events) Or maybe I'm wrong and it's just cheaper to ask the 용인government to use a small playground than renting a center.

Also, one person on Naver blog said how the circles doubled from last year at 20 circles, so there might be like 40-50 circles and the park might become overcrowded if they do announce it next year (since most will likely see it as the Korean Touhou event). (But again, the organizers may forsee this and change the location to a proper convention center, since they also had rain issues this year due to it explicitly being 100% outdoors)

Thank you for the information. By the way there is also 구작이 인기가 없는 건 액신님 탓이야!
It looks like most events this year were organized by Airdefence (including 온 동네가 환상향). As I understood 온 동네가 환상향 is not only about doujin sales and the doujin sales part is called 동방야시장. Even though it had 20 circles (and stalls) this year, the next event (미래세기의 초대장) is bigger (it has 23 circles (25 stalls)), but it is hard to say how big 온 동네가 환상향 will be the next year. In addition it looks like 환상몽원도 are expecting up to 50 circles.