Masaru Yotsuba

Matergriz, who is in his human name Masaru Yotsuba (四葉 勝, Yotsuba Masaru), is a 16 year old teenage Galvan boy from Galvan Prime who have been chosen as a Kamen Rider Grey Matter (仮面ライダーグレイマター).

Personality
He is Uzagi's best friend. He is very intelligent and has a photographic memory. Masaru is the perfect all-round student, consistently getting 100s in class and also being highly capable in sports. Yui sometimes prefers the company of Masaru, who is more of her intellectual equal. Hiroto often feels jealous and concocts bizarre schemes to keep them apart or to win Yui's attention. However, Masaru never gets angry at Hiroto and even willingly helps Hiroto whenever he has philosophical or scientific questions. Masaru is polite, respectful, and will never argue with or fault anyone even in the most ridiculous of situations – instead he will always say something positive to lighten the mood.

Devices

 * Omni-Driver: Transformation belt.
 * Omnicard Grey Matter: Transformation card.

Powers & Abilities
Grey Matter's small size belies his great calculative and technical intellect. He can create complicated machines from spare parts, understand the function of any device at a glance, and make sophisticated repairs to complex machines. Grey Matter's intellectual and analytical prowess aids him in succeeding his opponents in difficult situations. In conjunction, his intelligence makes him a natural problem solver, enabling him to think more strategically when brute force is inefficient.

Grey Matter can sometimes manipulate living things by stimulating certain parts of their nervous system, if such beings can be controlled by an external stimulus.

He can climb walls.

He also have a ninja skills.