Then Reimu finds a way to destroy Yukari at the end so she can keep the Gap Gun.
After that, Yukari revives, finds Reimu, and the whole scenario plays out again, this time with Yukari letting Reimu leave Gensokyo.
What if Jade the Necromancer from Tales of the Abyss (who is also the father of fomicry) met Nitori Kawashiro?
Nah. Better question. What if Frog from Chrono Trigger met Cirno?
This is in the ending where Magus is with the party and Frog is still a frog... there's other endings where he's human again, but they mess with this question.