In this picture book, Piggie regained his spirits and re-energized by getting in touch with various "happy signs" of his friends and recalling his own "happy signs". Not only do the grown-ups sometimes lose energy, but also children. If everyone can read this picture book and discover each other's "signs of being happy", it would be nice to play vigorously and happily at the same time. Everyone has a "happy sign"! When you are not energetic, think about the "Happy Sign"!