けろけろけろっぴの大冒険~ピンクのきのこ

This is the story of Keroppi and his search for the pink mushroom which could cure all illnesses. It all started with his father Keroppa finding out that Keroppi's brother Kurtis had the case of the frog fever, which makes him lose his voice. Even though it lasts ten days, Keroppi didn't want to wait ten days since Kurtis had a secret to tell him.