Tenjuro Banno (蛮野 天十郎 Banno Tenjūrō) is a scientist with a superiority complex and the main antagonist of the series. He is also father to Kiriko and Go Shijima. He was one of Krim Steinbelt's colleagues, but he secretly held a grudge against Steinbelt after the man created the Core Driviars. Fifteen years before the events of the television series, Banno attempted to create an artificial life form that can transcend humanity, but the dead ends in his research slowly drove him mad by the time he convinced Steinbelt to share the Core Driviarto provide him with the Core Drivar technology that he used to create the Roidmudes. Steinbelt was horrified at his colleague's depravity after he watches him torture Roidmude 002 who he had made impersonate a businessman that had slighted him. Steinbelt turned his back on Banno, who secretly stole the man's mind link technology as well. Banno completed the Roidmude technology on his own, implanting within them a desire to eradicate humanity, and allowed the completed Roidmudes to fatally wound himself so he could upload his mind into a computer tablet, as well as kill Krim Steinbelt. The tablet ultimately ended up in the hands of Brain, who uses the tablet to reset rogue Roidmude Cores. Banno also caused the first Global Freeze after releasing the Roidmudes in northeast Asia, particularly in Japan, the Koreas, and Russia. Though Go later manages to steal the tablet from Brain to save his father, Banno has been pretending to be hostage to the Roidmudes, as he wants to manipulate the Kamen Riders for his own ends. He reveals his true colors when Kiriko is abducted by the Tornado Roidmude. With the help of Roidmude 004, Banno creates a copy of the Drive Driver as the Banno Driver (バンノドライバー Banno Doraibā) and then removes the Core of Roidmude 006 to house his mind and transform into Gord Drive (ゴルドドライブ Gorudo Doraibu). He reveals he has no love for his family and considered them his slaves like he treats the Roidmudes. As Gord Drive, Banno seeks to initiate the second Global Freeze, but this time he seeks to propagate it worldwide by using himself as the fourth Roidmude to power the machine Sigma Circular, even planning on sacrificing Medic to complete his plans. Brain's self-sacrifice to save Medic does not thwart Banno's plans, as his energy is enough to power Sigma Circular, using the Special Situation Defence Center (特殊状況下防衛センター Tokushu Jōkyōka Bōei Sentā) as his base of operations. Roidmude 004 manages to save Banno from being apprehended by the Kamen Riders by self-destructing allowing his escape, but Banno as Gord Drive is confronted one last time by Chaser and Mach. He defeats both Kamen Riders and prepares to kill his own son, but Chase transforms into Mashin Chaser one last time and temporarily stops Gord Drive, leading to his own death. Go, pushed over the edge by Chase's admiration of humanity at his death and Banno's callous response to it, uses the Signal Chaser to transform into Kamen Rider Chaser Mach, ultimately destroying Banno's body in Roidmude 006. With his consciousness still remaining in the Banno Driver, Go reverts from his transformation and uses the Shingou-Ax to destroy the Banno Driver, ending Banno's reign of terror on humanity all while his father pleads for mercy despite all he has done to the Roidmudes and his family.
While within Brain's tablet, Banno has the ability to manipulate data in various ways. He can produce tentacles that can attack and deliver painful electric shocks, heal people infected by Roidmudes by restoring their bodies to normal, and he can even produce a digital shield to protect people from Roidmude attacks. As Gord Drive, his appearance is based on both versions of Drive's Type Speed, such as the current Drive Type Speed helmet and Proto Drive's body armor, while his power is similar to that of an Over-Evolved Roidmude, or rather, he himself is the Over-Evolved Roidmude, and is able steal the arsenal of compatible Kamen Riders, including the Shift Cars and Signal Bikes, until Rinna Sawagami develops a special data coating that protects them from falling under his control, but not their weaponry.
Tenjuro Banno is portrayed by Masakazu Morita (森田 成一 Morita Masakazu).