You know, Kurama in Gensokyo could make for an interesting fic by itself. Watching him interact with all those quirky characters would be hilarious. And just as soon as he's settled in and getting used to a peaceful life all hell breaks loose when Obito uses Kamui to break into Gensokyo and bring Akatsuki with him so he can retrieve Kurama and revive the Juubi. Yukari of course sleeps through all this or tells Kurama it's his fault and he should clean up his own mess.
Even better, Obito and rest of Akatsuki get their hands on some spell cards and Kurama, Reimu and Marisa have to defeat them in a series of proper danmaku battles.