A black-haired lizard/mantis monster. He can detach the blades on its back to throw them and use them as weapons. He is commanded by Bosgun who accompanied him to attack Kotaro where Gynakamakil manipulated aluminum cans. The second time, Joe disguised himself as a bride to lure out Gynakamakil. While Kotaro and Joe were fighting Gynakamakil, Bosgun used his new sword on the car that Reiko was hiding in and made off with her. When Kamen Rider Black RX caught up to where Bosgun and the Chaps had the other brides, he ended up fighting Bosgun and Gynakamakil. Kamen Rider Black RX became Robo Rider so that Bosgun's sword could not penetrate him, resulting in his destruction. He then followed up with an attack on Gynakamakil. Robo Rider reverted to Kamen Rider Black RX and destroyed Gynakamakil with his Revolcane. Gynakamakil was later revived by Maribaron as part of the Spirit World Kaijin Army.