By complete accident, Inigo and Sakura fell into the void below Valla, and wake up in a lightless forest. By chance, they come across the inhabitants of the world they fell in, a bunch of multi colored ponies. Knowing no other option, the two begin to work with the ponies to find a way back into their world, so that they may aide in finishing the fight.
Someone else fell down with them, however, and unlike other such individuals, he isn't too keen on letting the people of this world live.