What does it mean to be somepony? To truly exist? To know love, laughter, jealousy, anger; what does it mean to live? Organization XIII seeks these answers, and will do so regardless of the cost. For what does a Nopony care for the morals of a Whole Pony?

Hyxs wakes up one day with no memory of who, or what, she is. But then a cloaked stranger comes to her, and gives her a new purpose in life; to open the citadel of Kingdom Hearts, and become a Whole Pony again. To do this she must travel through the many worlds of the multiverse, and collect the Hearts of others. But when a purple mare and her companions get in the way of the Organization's goals, so will begin another clash of Light and Darkness.

(Crossover due to its plot design; no Sora, no Mickey, just ponies)

Other side of the story: Somepony