I love love love me some YukaReimu, but this felt a little...under cooked. They were too busy trying to be cool, and they didn't really dedicate enough time to make the mechanics of whatever was going on make any kind of sense. Yukari basically set up all of Gensokyo as...what, a fantasy world for Reimu? She likes Reimu but kind of just because, what, Reimu told her to? And Reimu doesn't remember her? And Reimu didn't have a name before?
Why though?