Where do you get Mieu Wing in Tales of the Abyss

Sometime after saint binah sinks, go to Tataroo Valley (north of Chesedonia). If its still nightime then wait until after the engave people. Go north until you get to the river. Cross it and keep going on the path until right before you get to the clearing with the butterfly and tree. Use mieu attack on a wierd looking boulder sticking out until one cracks. Go inside. Warning! you can only do this if you have everyone in your party. warning x2 its best to this before you retrive the flightstone in daath so that you can get the chests with the unreachable ladders.