Ah, you're right. They do have to be polite.And she says she can't be bribed.
>"She's over there." *points to fairy*
You point her over in the right direction and set off with Reimu to find the fairy.
Upon arriving, you find her sitting in the same spot looking melancholy.
"Hi! Is this person able to help me get rid of that youkai?"
Reimu, "Yup, I'll get rid of it for you."
Fairy, "Thanks! Follow me and I'll show you where it is."
She leads the way to a very large tree with a door cut into the trunk.
"It's in here, but the door won't budge."