Takata Toy Store owner's only son, Xiao Gang (Sho Sakurai), inherited his father's genes and invented a giant robot dog "Dogman Wangwang" that can be used for fighting. He and his girlfriend Xiao Ai (Saki Fukuda) form the "Little Double Heroes" of justice and work hard to protect world peace. Their main opponents are the Durenbu Thieves, which are composed of the female thief leader Duo Longzhi (Kyoko Fukada) and her two followers, Tong Zila (Kendo Kobayashi) and Boyaki (Katsuhisa Namase), one fat and one thin. Duo Longzhi works for the god of thieves, Skull Shell, and they are ordered to search for the legendary Skull Stone fragments that can fulfill any wish. The father of the girl Shoko (Anri Okada), Dr. Kaieda (Takashi Abe), is an archaeologist who suddenly disappeared while searching for the Skull Stone. The little double heroes who learned the details from Shoko launched a series of exciting and fierce battles with Duo Longzhi and his group to stop the Skull Shell's conspiracy to destroy the world...