In Japan, bonsai has often been thought of as a hobby for the elderly, but it is now known around the world. Bonsai vocational schools have been opened in Italy and France, and bonsai exhibitions have been held in South Africa and Argentina. Exports from Japan have grown tenfold in the past ten years. Bonsai is now a universal word. People came from around the world to attend the World Bonsai Convention in Saitama. Why is it popular among foreigners? We search for cools of traditional Japanese culture through bonsai.