In this case, Reimu has to do it, Marisa just wants to be with Reimu, and Sanae is no longer held back by common sense.
Why do you exterminate Youkai?Well that's becauseit's my job. Why do you exterminate Youkai?Huh?Just asking me that all of a sudden~Why do you exterminate youkai?Not a clue.I just go along with the mood.For the safety of the village...
Just kidding.
I get to be with Reimu too.