Before the Legendary Days event, I was in the Invaded Kingdom having won all of the battle drop girls available, up to that point. This included event girls from Valentine's Day, A Second Chance, and Spring Break. Since the Legendary Days event began, I completed The Juy Sea, leveled Edwarda up to 100 (for a few days, now) and haven't won any of the battle girls, nor Levitya. That is a drastic change in drop rates. Either I was incredibly lucky, up to that point, or some code was changed.
Either way, I'm quickly losing interest in the game, since I can't win new girls.