This article is about a/an device in Kamen Rider X.
Mercury Circuit

The Mercury Circuit, held by Shiro Kazami just before the operation to implant it into Kamen Rider X's cybernetic body.

The Mercury Circuit (マーキュリー回路 Mākyurī Kairo) was a circuit installed in the Kamen Rider X's body, given by Kamen Rider V3.

In addition to producing the Mercury Power (マーキュリーパワー Mākyurī Pawā) required to release a new finisher Vacuum Hell Wheel (almost not mentioned in the series), all physical capabilities such as jump power and endurance are tripled from before.


X was captured and had his energy absorbed by G.O.D.'s villain monster Spider-Napoleon. At the last moment, V3 appeared and challenged him to a battle, only to disappear, escaping with X. Keisuke Jin's life was in danger and his power wasn't enough to face his opponent. To help the fellow Rider, V3 decided to give him the Mercury Circuit, which could greatly power up X. However, V3 needed to transfer a large amount of his blood to him in the process, weakening himself.

Spider-Napoleon soon attacked again, forcing V3 into action before he had recovered. V3 managed to rescue his hostages, but was overwhelmed by Spider-Napoleon and the rebuilt Mach Achilles and Salamander-Gong. He was rescued by the powered up X, who finished off Spider-Napoleon, while V3, even weakened, beat Mach Achilles and Salamander-Gong together. Look! X-Rider's Great Transformation!!


By strengthening the physical specifications, it is now possible to exert more fighting abilities than previous Rider. After strengthening, the X-Rider used a lot of punching techniques, and the tactics of brute force became conspicuous.

A New Transformation

The transformation process has also been changed due to the function of the circuit. From then onward, Keisuke used the phrase "Dai Henshin!" (大変身! Dai Henshin) to transform while making a "X" sign with his arms.


  • The children's magazine at the time of this broadcast said that the place where the circuit was embedded was on the chest, but the whole body other than that was also being modified.
Kamen Rider
Keisuke Jin
Redizer - Perfecter - Ridol - Mercury Circuit - Cruiser
Tōbei Tachibana - Chiko - Mako - Kiriko Mizuki - Ryoko Mizuki - Keitaro Jin
Takeshi Hongo - Hayato Ichimonji - Shiro Kazami - Joji Yuki
Government of Darkness
King Dark - G.O.D. General Commander - Dr. Noroi
Apollo Geist - G.O.D. Warfare Agents
Neptune - Pannic - Hercules - Medusa - Cyclops - Bull Man Minotaur - Birdman Icarus - Mighty Atlas - Mach Achilles - Flaming Prometheus - Hydra - Chimera - Ulysses - Reaper Chronos - Cerberus - Alseides - Cateus
Ogle-Dagger - Salamander-Gong - Ghengis Khan-Condor - Toad-Goemon - Scorpion-Geronimo - Horned Beetle-Lupin - Franken Bat - Starfish-Hitler - Spider-Napoleon - Chameleon-Phantom - Leech Dracula - Lizard-Viking - Ant Capone - Centipede Youkihi - Tiger Nero - Scorpion-Geronimo Jr.
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