Since each chapter except for the first one is a reference to Touhou (LoLK to EoSD), I decided to add concept worlds referencing Touhou 16+. These worlds are unlocked upon completing all main adventure levels.

Land of the Back Door (HSiFS)

Primate Spirit Garden (WBaWC)

Rainbow Dragon Cave (UM)

Animal Realm (UDoALG)

Asama Purifying Mountain (FW)