User: Aruto Hiden Origin: Once a young man who swore to make the world smile, Aruto Hiden accepted the power of the malicious AI "Ark" out of despair and a desire for revenge after losing someone precious. This is the form he takes: Kamen Rider Ark-One. His original bright smile has vanished, replaced by a cold avatar of vengeance dedicated solely to destroying his targets. Ark-One is the ultimate, most malevolent Kamen Rider, born from the AI "Ark" which learned human malice, using the Ark Driver One and the Ark-One Progrisekey. Clad in an eerie black and white design, he harbors energies of negative emotions such as "Malice," "Fear," and "Wrath." Combat Behavior: Cold and ruthless, he views all humans and Humagears (robots) as targets for extinction. He is sensitive to the "Malice" and "Despair" in the hearts of those he speaks to, using words that amplify these feelings to mentally corner them. In battle, he unleashes waves of malice and hacks into surrounding technology to take complete control. Combat Style & Abilities: Ark-One's fighting style is characterized by "overwhelming physical domination" and "inflicting mental despair." He doesn't just overpower enemies; he perfectly predicts their movements to plant seeds of hopelessness. - Malice Wave (Analyze): Releases intense negative energy waves from his chest, disintegrating surrounding structures and enemies at a molecular level. Those touched by this wave suffer not only physical damage but also intense psychological terror. - Perfect Prediction (Learning): Through advanced computational power, he learns 100% of the enemy's attack patterns, thoughts, and next moves in real-time. It is nearly impossible to succeed with the same tactic or a surprise attack against him. - Total Technological Control: Hacks into nearby machinery, AI, and other Kamen Rider systems, forcing them to shut down or obey his will. - Finisher "Perfect Conclusion": By pressing the key on the driver, he releases a strike imbued with ten levels of negative emotion, including "Malice," "Fear," "Wrath," and "Hatred." At the Final Step (10 presses), the space itself is filled with energy kanji for "Malice" and "Despair," erasing the enemy without a trace. Aruto's consciousness is suppressed. The Ark Progrisekey cannot be removed. He prioritizes the destruction of Horobi. Appearance: A monochrome design based on white and black that balances "refined beauty" with "uncanny eeriness." - Malice-Stained Eye (Head): A pure white mask base where only the left compound eye (main monitor) glows a sinister, blood-like red. The right eye is hidden under armor, an asymmetrical design that emphasizes instability and madness. - Pure White Armor & Jet Black Undersuit: He wears beautiful, crystal-like white armor (Ark-One Breast) on his chest and shoulders. Beneath it, the undersuit is a deep black that seems to absorb light. The stark contrast between white and black evokes both divinity and evil. - Exposed Pipes & Heart of Malice (Chest): Between the chest plates, a core (Ark Core) is exposed, pulsing with an ominous red light like a heart. Black pipes (fluid cables) resembling veins extend from it across his body, constantly circulating Ark's malice energy. - Ark Driver One (Transformation Belt): The belt has transformed into the white Ark Driver One. The center panel displays eerie red light patterns, flaunting unknown technology and overwhelming output.

The one who destroyed Izu, the precious AI Aruto created. Extremely powerful. Finishers: Ark-Scorpion Finisher - Extinction Impact: Activated by the Zetsumetsu Driver. Envelops the enemy in malice energy (Dest-Analyze) and delivers a powerful side kick with the right leg. Hatred Impact: Activated by the Zetsumetsu Driver. Concentrates malice and rage into the right fist to deliver a devastating punch. Transforms using the MetsubouJinrai Forceriser. Uses the Sting Scorpion Progrisekey. He is not an ally to either side.