Sometime during his youth, Jōji Yūki was abandoned and was considering suicide when Great Leader of Destron personally intervened and adopted him. Yuki considered him his savior and willingly swore allegiance to Destron.
He serves loyally for Destron’s cause as top scientist until a jealous Marshall Armor frames him for being a traitor of Destron to cover up his failures of defeating Kamen Rider V3. As a result, he is sentenced to be tortured to death by being dipped into a pool of acid, which results in the loss of his right arm. 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 Great Leader of Destron is so strong he is willing to sacrifice himself to protect him by jumping in the way of V3′s Fatal Kick. When being asked by Kazami why he does such a thing he reveals his past relationship with Great Leader of Destron and admits that he simply can’t let his savior be killed right in front of him. He pledges himself to V3′s mission after this.
Near the end, he supposedly dies in a Pluton Rocket explosion. Kamen Rider V3 cries out that he is Kamen Rider No. 4.
| Statistics | |
| Height | : 1750 cm |
| Weight | : 70 kg |
| Ability Perimeters | |
| Punching Power | : Unknown |
| Kicking Power | : Unknown |
| Maximum Jump Height | : 10 m |
| Maximum Running Speed | : Unknown |
| Finishing Power | : Unknown |
Techniques
- Rider Slash
- Rider Shooting
- Rope Arm
- Hook Arm
- Swing Arm
- Net Arm
- Sickle Arm
- Power Arm
- Drill Arm
- Machine Gun Arm
- Operation Arm
- Spray Arm
- Octopus Arm
- Blaster Arm
- Rider Machine
