Kai was taken by Nadakhan to use all his wish so Nadakhan could use his element power of fire. Kai was in panic he knew what happens if he use all wishes. He first wished that he wanted to go back Ninjago but Nadakhan brought him back to the old Ninjago. So Kai slightly became frustrated so he wished again.

"I wish you to take me back. Back when the girls were crazy for me. Back when anything was good!"

So he was in Ninjago now. But there where crazy girls chasing him.