Aya and Hatate have an amazing adventure traveling through different worlds, looking for a new place for youkai to settle.

First World: Falmart (Gate)
Second World: Super Mario RPG: Legend of the Seven Stars (pg 44)
Third World: Legend of Zelda: Ocarina of Time (pg 64)
Fourth World: Overlord (Maruyama) (pg 123)
Fifth World: Final Fantasy VIII (pg 142)
Sixth World: Redwall (pg 226)
Seventh World: Wheel of Time (pg 254)