Yusuke Urameshi never expected life as spirit detective, but after his near fatal fight with Rando and six months of grueling training with that old bint, Genkai, he thought he'd seen it all. Then, while on special assignment to America by order of Koenma, he and his grim reaper assistant, the lovely Botan, encounter what they assume to be a demon of an unknown kind and follow the sultry succubus into a portal at the base of a horse statue in the middle of a highschool in Canterlot, Colorado.

Upon arrival, however, they discover the succubus to actually be a magic, talking, pony princess from another planet in another universe inhabited by many more, magic, talking, ponies.

If Yusuke can suffer her and her friends (and Botan) for the month he's stuck on this strange, new world, and stop the sealed bad-ass in a can from the ancient world threatening them THIS time, he and Koenma are going to have a LOOOOONNNNNGGGGG talk that involved lots of kicking and screaming…