Joji Yuki (結城 丈二 Yūki Jōji) is the Secondary Rider from the television series, Kamen Rider V3. He is a former member of the organization known as Destron who becomes Riderman (ライダーマン Raidāman) to seek vengeance againts Marshall Armor. He is also known as The Avenging Demon or Kamen Rider 4 (仮面ライダー4号 Kamen Raidā Yongō).
Sometime during his youth, Joji Yuki was abandoned and was considering suicide when The Great Leader personally intervened and adopted him. Yuki considered him his savior and willingly swore allegiance to Destron. He served loyally for Destron's cause as top scientist until a jealous Marshal Armor framed him for being a traitor of Destron to prevent Yuki from competing with Yoroi for a higher position. As a result, he was sentenced to be tortured to death by being dipped into a pool of acid, which resulted in the loss of his right arm. Yuki barely escaped with his life when his followers and assistants of the Destron Science Divison interrupted the execution and blew up the base with a bomb, allowing them to escape.
At first, he only sees Marshall Armor as his enemy and not the Destron Organization itself; furthermore, to prove his innocence to Destron, he seeks out to defeat Kamen Rider V3. However, he learns the truth about Destron and eventually joins Kamen Rider V3's cause. Even after joining V3 his devotion to The Great Leader was so strong he was willing to sacrifice himself to protect him by jumping in the way of V3's Fatal Kick. When asked by Kazami why he did such a thing he revealed his past relationship with the Leader and admitted that he simply couldn't let his savior be killed right in front of him. He pledges himself to V3's mission after this. Even after pledging himself to V3`s mission, Riderman tried one last time to negotiate with his adoptive parent before finding out the truth. After learning Destron`s plans, he seemingly sacrificed himself to save the people of Japan from a Pluton Rocket explosion. Kamen Rider V3 then cried out that he is Kamen Rider 4.
In reality, he manages to survive. It is explained how he survived the explosion and landed in Tahiti where he lost his memory, but regained it when fighting a crab kaijin who was really a resurrected Marshal Armor.
Riderman, who's shown alive for the first time since his death during his meeting with his successor, X, reveals that he had been in Tahiti. The 5 Riders, following one of the Franken Bat's bat spies head to one of G.O.D's bases. V3 faces Icarus, Cerberus, Neptune and Chronos before regrouping with the other Riders, when he took on and destroyed Icarus and Neptune. Afterwards, the five Riders face Franken Bat. The four Riders helped X execute the "Rider Super High Kick" technique, destroying Franken Bat. They invaded a G.O.D. base and faced King Dark, but the entire complex was merely an illusion, which disappeared while King Dark laughed at them.
Riderman, who had been fighting against Armored Knight in Greece and followed him to Japan comes into conflict with Stronger, believing that each other were helping Delza, but soon V3 appears and clears up the misunderstanding. V3 and Riderman leave and face the Delza Army troops who destroyed a dam, with Riderman facing Armored Knight and V3 taking on Commander Jishaku. However, Riderman is easily defeated and V3 is caught into a trap and is swallowed by a fissure.
Amazon and X rescue V3 and Riderman, and they soon meet Stronger again, who had been joined by Rider 1 and Rider 2 in their absence. The seven riders, which would be known as the Seven Legendary Riders, marched against the Delza Army, who had captured Tobei Tachibana. Finally, Stronger finishes off Marshal Machine. They meet Tachibana, but soon a familiar voice welcomes then, Delza Army's Great Leader.
The Great Leader reveals that he had been behind the Delza Army, Destron and other previous evil organizations opposed by the Riders. He takes on the form of a rock giant, impervious to the attacks of the Riders. However, they combine their powers and go into his body. There, they find a giant alien brain who self destructs in an attempt to kill all seven Riders, however, they all escape successfully and leave, reminiscing everything they've gone through so far.
The evil organization Neo-Shocker moved ahead with its plans of global genocide. Joji Yuki, Riderman, alongside the other Seven Legendary Riders fought around the world against it, leaving Japan's protecting to the new Kamen Rider, Hiroshi Tsukuba, Skyrider.
Kazuya Oki, Kamen Rider Super-1, fought against the Dogma Kingdom to stop them from awakening an ancient weapon. However, in his way stood the Dogma Revenge Corps, troops of rebuilt cyborgs from Dogma Kingdom and Neo-Shocker. When he seemed overwhelmed by his enemies, Rider 1 suddenly reappeared, followed by the other 8 previous Riders, all alive. V3 tells Super-1 to let that battle in their hands, and soon they fight against Dogma's troops to open way for Super-1. V3 briefly faces Dogma Fighters, Gyosutoma, ArigiThunder. Fighting alongside Riderman, V3 finishes off Zombieda with a throw while his partner does the same to Ganigannii. V3, Riderman and X go on to use a triple Revolving Kick to finish off, respectively, Kamagirigan, Snakecobran and ArigiThunder. Thanks to the help of the Riders, Super-1 reaches Dogma's troops on time and stops them. After the battle, the Riders show themselves to Super-1 and his friends, and promise to fight for humanity's future together.
The Badan Empire, led by Ambassador Darkness, spread its claws around the world, and, to face it, the nine Riders came together. When Badan initiated its Space Break System, a destructive dimensional weapon, all 9 Riders gathered in Japan to stop them. Shiro Kazami coordinated an operation to stop Badan from getting Badanium 84, fuel for its weapon. With each Rider targeting a different transport, V3 stopped Dokuga-Roid from carrying the Badanium 84 and destroyed his truck, but Dokuga-Roid himself escaped while V3 faced his Combat-Roids.
Meanwhile, Super-1 and Riderman saw themselves facing a warrior called ZX, who had been fighting against Badan too. V3 arrived and stopped ZX, telling him that they're all enemies of Badan and want to destroy the Space Break System. Along with Riderman and Super-1, they explain to ZX, Ryo Murasame, the history and meaning of being a Kamen Rider, and, finally, he decides to join them, as the 10th Rider, Kamen Rider ZX. Afterwards, Badan's base was located, and all 10 Riders went towards it. Ambassador Darkness welcomed them and sent all of Badan's troops against the Riders. V3 faced Dokuga-Roid and his Combat-Roids again, and after a long battle managed to destroy him by throwing him onto a fallen Yamaarashi-Roid. Afterwards, V3 and Rider 2 teamed up against Jūjin Ōmukade, a revived Geddon monster. however, before the battle could be finished, Ambassador Darkness attempted to use hostages to make the Riders surrender. His plan fail due to Super-1's interference and Ambassador Darkness decides to use the Space Break System, only to destroy Badan's remaining troops. After V3's call, the ten Riders gather their power with Rider Syncro, weakening Ambassador Darkness and allowing ZX to finish him off. After Darkness is defeated, evil energy gathers in the shape of a giant skull, The Generalissimo of Badan, giving farewell to the Riders and laughing at them.
V3 bestows upon ZX the official name Kamen Rider 10 and soon all Riders part ways again to continue their battle against evil around the world.
Riderman, alongside the other Ten veteran Kamen Riders, fought against secret forces of the Crisis Empire spread throughout the world, defeating them in each country. However, Crisis' main forces, in Japan, still remained and they prepared a final offensive. Rider 1 called all Riders to a meeting in a secret facility in Arizona in the United States, to prepare for the upcoming battle, where they'd go to help Kamen Rider Black RX, the Kamen Rider that was defending Japan at the time. The 10 Riders split into two groups, which fought against each other. Group 1: Rider 1, Rider 2, V3, Riderman and X; and Group 2: Amazon, Stronger, Skyrider, Super-1 and ZX. During the training, V3 and Riderman often could be seen fighting together. After Crisis made a public announcement regarding its invasion of Japan, the 10 Riders finally left to the final battle.
After Crisis' war declaration, they immediately sent Gran Zairus, which landed on Earth like a meteor, destroying an entire island. Naval Commander Bosgun moved to attack Black RX, soon receiving help from Gran Zairus, who could resist all of RX's attacks. When Gran Zairus is about to finish him off, the 10 Riders finally arrive, rescuing RX and quickly escaping. Riderman and the others introduce themselves to Kotaro Minami, Black RX. Bosgun finds them, and proposes a duel against Black RX, however, Kotaro's friend, Kyoko Matoba, V3, Skyrider and Super-1 soon notice Chaps hiding around the area to prepare an ambush, finishing them off. Following Rider 1's words, Kotaro decides to face Bosgun in a fair match while the other Riders watch, and finishes him off. Meanwhile, Gran Zairus easily rips through the Japanese defense forces and brings down the city with his unmatched power. Kotaro leaves to fight him again, and, after some hesitation, Riderman and the other Riders follow him.
The 11 Riders face Gran Zairus, but even a combined Rider Punch with the power of the 11 Riders is useless against him. Gran Zairus transforms into a flaming rock, burning above 1000ºC, and easily knocks out Riderman and the other Riders. In the end, Black RX takes the battle and manages to destroy Gran Zairus, forcing it to self-destruct, but seemingly explodes with it.
Afterwards, Riderman and the other Riders helped evacuate the city's population and started to plan defensive measures for the next battles. However, soon the 10 Riders saw themselves facing Spirit World Demons, resurrected Crisis warriors. V3 faced the Harmful Imp and Ant Runt alongside Rider 1, successfully counter attacking, and later defeated Erigitron by himself, but they soon recovered from their attacks with no damage. When the battle seemed hopeless, Colonel Maribaron, the one behind this attack, revealed that the monsters wouldn't die as long as she kept a set of golden feathers with her, but Black RX returned, alive, stealing the feathers, stopping and destroying the monsters by himself.
After Black RX returned, the 10 Riders decided to spread themselves to observe and take on the Crisis forces, while Black RX protected his friends. Like usual, V3 and Riderman left together.
Wanting revenge against Black RX, a powered up General Jark, commander of the Crisis forces, Jark Midler, kills Sunkichi and Utako Sahara, who had helped Kotaro in the past, while taking their children as hostages. However, Kamen Rider Amazon saves the children and is quickly followed by V3, Riderman and X. V3 orders Amazon and X to take the children to Kotaro, while V3 himself and Riderman face Jark Midler. However, there's an overwhelming difference in power between them, and V3 can't even damage him. Some time later, V3 and Riderman are launched through the air, falling downtown, near a combat zone where Kotaro was helping. In a fair duel, Black RX ends up victorious over Jark, destroying him while the other Riders watch in amazement.
The Emperor Crisis calls Kotaro for a personal meeting. However, Rider 1 and the others decide to follow him too. The emperor offers Kotaro the chance of becoming the commander of Crisis' invasion forces, however, after Kotaro refuses, General Dasmader appears alongside a group of Chaps and attacks Kotaro. Riderman and the other Riders arrive and face the Chaps troops, but soon the entire cave is destroyed by the Crisis Fortress called by Dasmader. Black RX boards the fortress and destroys Dasmader, the Emperor and even Crisis itself. Meanwhile, the other Riders managed to survive the attack and meet RX after the battle was over. Following Rider 1's words, they all decide to part ways and fight evil around the world.
A mishap caused by the Greeed Ankh unintentionally altered the timeline which enabled Shocker to utilize a Cell Medal to create the Shocker Greeed which defeated the Double Riders and seemingly erased the legacy of the Kamen Riders from history. In 2011, after Kamen Rider New Den-O's attempt to repair the damage, he along with Kamen Rider OOO and M-Ankh awaited execution. However, it was revealed the Double Riders had their brainwashing removed by a Shocker scientist.
The Double Riders joined with New Den-O and OOO to fight Shocker's forces, but were eventually defeated. When the order was given to kill everyone, V3 suddenly appeared, asserting that there were more than four riders. V3 was soon followed by Riderman and all the other revived riders that came after him, as even though Rider history was changed, the people's memories haven't changed.
After the riders were united, they faced off against Shocker's Great Leader. Later, when joined by a force of extra riders, Riderman and all the other riders got on their motorcycles and performed the "All Rider Break", ramming into the Rock Great Leader and defeating it once and for all.
A meteor shower hit various points of Earth, bringing with it time anomalies, monsters and the interest of the shadowy organization Foundation X. Kamen Rider V3 and Riderman head to a meteor landing site in the Mediterranean islands, where they find a large army of Pseudo Yummies, fighting against them alongside Riderman. Afterwards, V3 and Riderman gathered with the other Seven Legendary Riders in Japan and infiltrated a Foundation X secret airport to stop Lem Kannagi, who was leading a plan to control energy sources around the globe and also their operation regarding the meteors. However, they're all taken by a trap and Riderman is sealed in an Astroswitch. Later, Kamen Rider Fourze finds the seven sealed Riders, and with Kamen Rider OOO's help, releases all of them at once. V3 warns them that Kannagi will receive a full charge of cosmic energy if he reaches space, which would make him invincible according to Riderman, and he needs to be stopped now. Meanwhile copies of the Greeeds and Sonozaki Family Dopants approach the group, standing in their way. The Seven Riders stay behind facing them, while Fourze and OOO head to stop Lem Kannagi. Riderman fights against a copy Mezool and finished her off with his Rope Arm. Meanwhile, OOO and Fourze managed to stop Lem Kannagi in space.
Joji Yuki is a loyal and selfless person at heart. Although originally blinded by his loyalty to his adoptive parent (despite nearly being killed by him through a pool of acid) for saving him, he eventually came to understand Destron`s true motive and selflessly risked his life to save the people of Japan. At first burning with revenge like Kazami, Joji later understood what it means to be a Kamen Rider and was inspired by him to fight for justice than revenge.
- Rider Height: 190 cm
- Rider Weight: 110 kg
- Ability Perimeters:
- Punching Power: 5 tons
- Kicking Power 3.5 tons
After his body was altered, in order to save his life, Joji Yuki would become Riderman by holding his hands up, summoning his helmet to his hands, and placing it on his head. Once this was done, his body would adjust to the helmet, revealing his cybernetic alterations, in particular allowing him to change out his prosthetic arm to any number of different weapons or gadgets, depending on the situation.
- Rope Arm (ロープアーム Rōpu Āmu): Riderman's default/primary Cassette Arm, which is used in various ways: as a means of escape, climbing, and in combat. The arm itself has modified attachments for Yuki to use and adjust to various situations:
- Hook Arm (フック－アーム Hukku Āmu): A hook attachment for climbing and combat.
- Swing Arm (スウィングアーム Suwingu Āmu): A mace attachment, which can be extended and used as a flailing weapon.
- Net Arm (ネットアーム Netto Āmu): An attachment where Yuki's arm can shoot out a net to capture and restrain enemies (by Kamen Rider Spirits, it appears that this net is fireproof).
- Sickle Arm: An unused attachment, which has been seen in various promotion; and yet, wasn't used in the series. Based on the photos, it is assumed that it's simply used for combat.
- Power Arm (パワーアーム Pawā Āmu): One of Riderman's strongest weapon, which increases Yuki's attack in battle. Its primary use is to hack away at both obstacles, such as doors, and opponents. This weapon could've been easily used as a finishing attack, according to some fans. This weapon is the first instance of a Rider using a blade against a monster, which would later be a frequent armament in the Heisei Era-Riders.
- Drill Arm (ドリルアーム Doriru Āmu): Another weapon could've been easily used as a finishing move. It was only seen being used as an infiltration tool. It must be plugged in order for it to work best, although it will still work otherwise (by Kamen Rider Spirits, it appears to work just fine without external power).
- Machine Gun Arm (マシンガンアーム Mashin Gan Āmu): This weapon was first seen in the Kamen Rider Spirits manga. It was used to destroy the revived Marshal Yoroi in the manga, which had the appearance to be a regular machine gun. This weapon is the first instance of a Rider using a gun against a monster, which would later be a frequent armament in the Heisei Era-Riders.
- Operation Arm (オペレーションアーム Operēshon Āmu): Only seen in Kamen Rider Spirits, volume 11. He used it to repair V3's belt, after its destruction by Soutern Cross
- Riderman is currently the only secondary Rider that is counted as a main Rider, due to Shotaro Ishinomori's decision, which had V3 name Riderman as "Kamen Rider 4" post-mortem.