Hello)
-There are 5 main story Characters, and lot's of additional ones.In this update of the game there are 3(Check Witches Trainer to see everyone else);
-For tags refer to the f95 thread, please.
-Story is well explained in the overview, if you want more - just play the game. This one is more a puzzle then a visual novel, if you want deep story and a big game world - check the Witches Trainer instead(they are in the same universe, and plot is happening in a very near timespace);
-I would say that One would be happy with amount of present ones.