/jp/ - Otaku Culture

According to wiki, EoSD happens in 2003, and "Marisa and Reimu are indirectly referred to as "children" in Chapter 22's first half (2001)". Children are people below 12 yo, but the girls does not seem to be little kids in CoLA. We can assume that Reimu and Marisa have around 7~12 years in that printed work.

Let's accept that both are 9 years old in CoLA's chapter 22. Following that conjecture:
EoSD: 12 yo (2003)
MoF: 16 yo (2007)
DDC: 22 yo (2013)

LoLK happens in 2015, therefore the protagonist are only 24 years old. However, this is a conjecture, problably their ages ranges at 21~26 yo. One more thing: ZUN could compress or expand Gensokyo timeline anytime he wants to do the girls age slower.