The price that Princess Mizuki paid when she made that wish was to never mature and be stuck at the mental age when she did the wish. One would think that this would have prompted the Dragon Turtle King to emerge from the hidden realm and search for Urashima Taro, but he did not. He does not know the dangers above as he would have left his realm unprotected. He is also like the Four Cardinal Divine Beasts as they cannot leave their own places.
The Dragon Turtle King tried sending some guards to fetch Urashima Taro, but the princess also wished for the safety of the boy. Every being that intends to take Urashima Taro or kill him will always fail. The Cintamani basically influenced probability to the point that anyone that harms Urashima Taro would be unlucky. This also had consequences to the princess as she felt her luck decrease.
