Tsubasa RESERVoir CHRoNiCLE

As Syaoran, Fye, Kurogane, Sakura, and Mokona arrive to the next world Syaoran collapses of fatigue due to the previous battle. An elderly woman offers her home for them to rest and also tells them the story of the castle. She tells them that if they make it up there alive a wish will be granted to them, but many have tried and died. They decide to investigate and see if it is the work of one of Sakura's feathers. What will be their wish?