Eita Kawai

Eita Kawai is a member of the Touto Institute of Advanced Matter Physics who is secretly an agent of Faust and an antagonist in Kamen Rider Build.

History
While Shingo Kuwata distracted Sento Kiryu, Eita Kawai lowered the security of the Institute so Blood Stalk and his squad of Faust Guardians could move in and claim the Pandora Box.

He allowed Blood Stalk to turn him into the Press Smash Hazard so he could hold off Ryuga Banjou. After being defeated by Ryuga, Kawai was reverted to his normal state by Blood Stalk with Cobra Steam Break. He accused Blood Stalk of being Takumi Katsuragi, the "Devil's Scientist", to which Blood Stalk responded to by changing his face to look like Shingo Kuwata's and rendering him unconscious.