Having established that the castle is full of Ninja Maids, I don't know that we need to discuss it more here.
It is interesting to think that the castle ties itself to its master, whoever that may be. It does reform each time it appears, so changing when someone new takes over makes sense.
Does lead one to wonder what the castle would look like if Shredder were in charge for a longer period of time...
 
    

When evil spreads across the land, and darkness rises and the monsters roam. When the creatures of the night make beautiful music, and the things that go bump in the night go bump with greater enthusiasm. When the world is in peril and is in need of a hero...

These guys are, sadly, the best the world can hope for. These are the adventures of the heroes of CVRPG. They mean well, they try hard, and occasionally they do the impossible...

They actually do something heroic.