Reimu's... mom? grandmom? great-grandmom? Reimu's (grand*X)+mom looks cool.
Looks like the whole ordeal was partially caused by how Gensokyo really relies on keeping up the facade of a dangerous, youkai-rampant world, when it's in reality a lot more regulated than that. Though there doesn't seem to be much harm in telling the truth to those who have already slipped beyond the line between natural and unnatural.
So, what's the best way to make a stubborn little vengeful spirit give up the fight? If you ask Reimu, it's not with violence, nor is it persuasion... It's both at once.