Bang-Gong is a blue monster who can shapeshift and transform into a shadow. He attacked Joe while he was with an old friend of his named Saila in an attempt to obtain her necklace and ended up injuring Joe in the process. Luckily, Kotaro transformed into Kamen Rider Black RX and battled Bang-Gong. Kamen Rider Black RX got them to safety in Ridron which also tackled Bang-Gong. Bang-Gong later kidnapped Saila. When Joe and Kotaro found her in an abandoned warehouse, they were ambushed by Bang-Gong and the Chaps. Kotaro transformed into Kamen Rider Black RX and fought him. As Bang-Gong swiped the necklace, Kamen Rider Black RX became Bio Rider and followed him outside. Bio Rider took back the necklace and then called forth his Bio Blade, which he used to cut off Bang-Gong's antennas and then kill him. He then got Joe and Salia out of the warehouse before the bomb planted by Gedorian blew it up.