Souji Kusakabe

Kamen Rider Dark Kabuto (仮面ライダーダークカブト Kamen Raidā Dāku Kabuto) is one of the major antagonists in Kamen Rider Kabuto.

Souji Kusakabe
Souji Kusakabe (日下部 総司, Kusakabe Sōji) is a mimic version of Tendou who was unknowingly captured by Mishima and used for the Hyper Zecter test. It is finally revealed that he is able to use the Dark Kabuto Zecter, a Zecter that mirrors the Kabuto Zecter. His Rider Form is similar to Kabuto's, but he has yellow eyes and his color has changed to black, with the exception of the top of his head, chest, and shoulders which contains dark red circuits which light up upon Cast-Off.

When he is first introduced, he was at the edge of time and space, existing in an unknown universe with Hiyori. Shown in episode 39, he seems to be a kind person that wants to protect Hiyori just as the original Tendou does. His innocence is shown when he observes the flowers and gives off a kind laugh. It is latered discovered that he is actually a human that was modified into a Native by Negishi's experiments, in hopes of turning all of humanity into Natives.

Fictional character biography
When Kabuto is carried to this dimension, the mimic Souji stands by Hiyori defensively, angered by the presence of Kabuto. Calling upon the Dark Kabuto Zecter, he changes into Dark Kabuto and prepares to fight Kabuto. During his first battle, he and Tendou initiate similar Rider Kicks, resulting in Tendou being defeated and flung back to the real world.

During episode 42, Dark Kabuto arrives in the real world through a bolt of lightning, and walks away with a childish look on his face. Later in episode 43, he appears before Kagami and others, stating that he's going to eliminate his other self. The mimic Souji eventually meets the real Tendou and the two engage in battle. The real Souji decides to allow himself to be defeated and thus when Dark Kabuto returns to the universe Hiyori is trapped in, Renge can track the portal and find Hiyori. When Tendou is on the brink of defeat, Gatack saves him and manages to convince him to fight Dark Kabuto, saying that he cannot allow himself to be defeated like that. Kabuto, now renewed with will to fight, defeats Dark Kabuto using the Hyper Zecter. However, Hiyori appears after a solar eclipse and says that she is happy to stay with Dark Kabuto in another world. After doing so, Hiyori changes into Sisryaworm and prepares to protect Dark Kabuto.

After Hiyori and Dark Kabuto return to their dimension, they meet up with Tendou once again, who says that Hiyori should come back. The mimic Souji asks Tendou if he can truly keep his promise of always being by Hiyori's side, and Tendou says he can't. However, he will protect Hiyori for as long as he can, fighting all those who do evil to the world, not because they are Worms. Soon after, Hiyori leaves and abandons Dark Kabuto. Furious, he arrives in the real world and assaults Hiyori, only to meet two more Reiji Nogis. The Nogi's then ask him to cooperate with them, telling Dark Kabuto that he does not know who he truly is. Refusing, Dark Kabuto leaves in a frenzy after attempting to fight the Nogis. After returning in episode 47 to challenge Tendou, he is defeated by Hyper Kabuto. The unconscious mimic Souji is then captured by Mishima once again.

After being tormented by Mishima and Negishi, who both state that he is a failure, he goes into an outrage, attacking Mishima. It is then that they tell this mimic that he was actually a human once, and was altered into a Native. In turn, he was told to mimic Tendou, creating who he is now. They forcefully copied the Kabuto Zecter, creating the Dark Kabuto Zecter, intending to have a powerful force of their own. During this moment, Tendou appears and uses Clock Up to rescue his mimic. However, the mimic escapes once again, only to meet Mishima once more. As Mishima transforms into Gryllusworm, the strongest Native, Dark Kabuto charges at him and is defeated.

After Dark Kabuto is captured once again by Mishima, it is revealed that they plan to drain his power and combine it with a fragment of the Native meteorite in order to convert the entirety of humanity into Worms. As Kagami arrives that their secret lab, he is defeated by Mishima and the humans that had become Natives. During the final moments, Dark Kabuto rushes out and captures Negishi, dragging him back into the explosion as Dark Kabuto transforms into a Native. He tells Tendou that he is leaving, and it is up to Tendou to protect this world now.

OOO, Den-O, All Riders: Let's Go Kamen Riders
Kamen Rider Dark Kabuto was part of a group of reinforcement riders led by Akira Date/Kamen Rider Birth to aid the primary riders in defeating the Rock Great Leader. All the Kamen Riders got on their bikes and performed the All Rider Break attack which destroyed the Great Leader.

Kamen Rider Kabuto video game
Kamen Rider Dark Kabuto appears with the other Kamen Riders in the Kamen Rider Kabuto video game, in his Masked and Rider Form, however this version of Dark Kabuto is very different from normal Souji Kusakabe, his personality is aggressive and fighting style is violent, his target is only destroys Tendou.

Forms
The Dark Kabuto Zecter (ダークカブトゼクター, Dāku Kabuto Zekutā) allows Souji Kusakabe to transform into Kamen Rider Dark Kabuto. As with all of the Zecters, Kabuto has two basic forms that he can transform into. His forms resemble those of Kamen Rider Kabuto in different colors.

Dark Kabuto Zecter

 * Owner: Souji Kusakabe
 * Device Type: (Dark) Kabuto Buckle ('Henshin' Belt)
 * Animal: Kabutomushi or Japanese Rhinoceros Beetle
 * Color: Black/Red
 * Cast-Off System: Flipping the switch-like Zecter Horn on the Dark Kabuto Zecter over.
 * Cast-Off Announcement: "CHANGE BEETLE"
 * Clock Up System: Slap the Switch-pads on the hip of the belt
 * Primary Finisher: (DARK) RIDER KICK - Dark Kabuto inputs the button sequence [1-2-3] on the Dark Kabuto Zecter and switches its horn-like lever back to its default position. When the horn-switch is flipped again, a tachyon charge surges from the Dark Kabuto Zecter to the Dark Kabuto Horn where it is refined, then directed down to Dark Kabuto's right leg, which is then executed as a flying kick, although various variations have been seen.
 * In PS2 tied-in video game, Dark Kabuto perform it by using heel-drop kick pinning the opponent in place, then crush him with tachyon-charged stomp.

Rider Belt

 * (Dark) Rider Belt: A different version of Kabuto's Rider Belt, designed by ZECT specifically for the Dark Kabuto Zecter. It is still unknown what different features it may possess. However, unlike Kabuto's one, it releases waves of black energy, rather than the normal blue.

ZECT Kunai Gun
ZECT Kunai Gun (ゼクトクナイガン Zekuto Kunai Gan): A versatile weapon with 3 distinctive modes: Ax, Gun and Kunai Mode.
 * “Ax Mode” becomes active when the gun barrel is held, and using the bladed butt of the weapon like a tomahawk; AVALANCHE BREAK can be performed in this mode.
 * “Gun Mode“, the default mode, fires high-intensity ion beam blasts and is equipped with tri-laser targeting; AVALANCHE SHOT can be performed in this mode.
 * “Kunai Mode” activates when the gun barrel is detached, unsheathing a short-dagger weapon good for its swift and easy handling; favored most when Dark Kabuto switches to Rider Form; AVALANCHE SLASH can be used in this mode.

Portrayal
Souji Kusakabe is portrayed by Hiro Mizushima (水嶋 ヒロ), who also portrayed the lead role of Souji Tendou. As Kamen Rider Dark Kabuto, his suit actor was Jun Watanabe (渡辺 淳). He was voiced by Tsuyoshi Takeshita who also provides his voice for Kabuto in Kamen Rider Climax Heroes