Twilight Sparkle enters the Canterlot Castle basement and releases the mare trapped in it. Turns out releasing a 495 year old vampire was not such a good idea in the end.
Go to sleep one night and wake up in a strange new world. Just another day in the life of Gensokyo's ordinary magician, Marisa Kirisame. But when dangerous youkai tag along, she may find that talking horses aren't her biggest problem...