These paper balloons are called "kamifusen" in Japanese, traditional toys for children. They can be inflated through a small hole, gently bounced on the palm of the hand. Because it is made of paper, the balloons are light enough for indoor play yet heavy enough that keeping it aloft is a challenge. It is reusable and also great for decoration.
This piggy balloon has a nose for fun and tlittle tail on the back.