一天，小女孩丽丽（西村千奈美 配音）和爸爸妈妈来到一家以青蛙为主题的游乐园玩，在误打误撞之来到了青蛙之国，中拔出了青蛙城堡里的勇者之剑，并且打倒了大蛇。在传说中，用勇者之剑打倒大蛇的勇者将被允许实现任何的愿望。

　　丽丽见到了青蛙王国的统治者，在国王将青蛙卵孵化之前，丽丽必须找到将希望之门打开的方法，如果没能在时限前完成任务的话，丽丽将被变成青蛙，永远的留在这个世界中。在这里，丽丽邂逅了一个名叫近藤的古怪男人，近藤总是主动接近丽丽，并且想要成为他的弟弟，这个男人真正的意图究竟是什么呢？

Lily went to an amusement park using the frog as its symbol character with her parents. At the Frog Castle of the park, she happened to draw a sword. It was said that the Frog King would grant any wish if one beat the big snake with the sword. When Lily beat the snake, she went to the Frog Land and met the Frog King. The king said she would become a frog if she couldn't open the Gate of Hope until a child would hatch from the roe in front of her. Suddenly, a man in suits appeared. His name was Knodo, and he was supposed to become her little brother. Lily thought it strange, and she ran away from him. He chased her. Then, they fell over into the water head over heels.

Lily möchte am liebsten, dass sich ihre Eltern scheiden lassen, weil sie sich so viel streiten. Als sie in eine wundersame Fantasiewelt gerät, will der König der Frösche ihr diesen Wunsch erfüllen. Doch da hat ihr noch nicht geborener kleiner Bruder auch noch ein Wörtchen mitzureden!