Sento Kiryu

Sento Kiryu (桐生 戦兎 Kiryū Sento) is a genius theoretical physicist who experiments with Fullbottles to further enhance his abilities as Kamen Rider Build (仮面ライダービルド Kamen Raidā Birudo) to fight against the evil Smash organisms. A man with no memory of his past, he was initially believed to be someone named "Taro Satou" (佐藤 太郎 Satō Tarō), but his true identity turned out to be Takumi Katsuragi (葛城 巧 Katsuragi Takumi). As the war for Pandora Box breaks out between the three countries, Sento accepts reality for what it is in order end the war that his previous identity had started.

In the past, he was a researcher at Touto Institute of Advanced Matter Physics who was murdered by Soichi Isurugi/Evolto upon discovering his true identity. Known among his colleagues as The Devil's Scientist (悪魔の科学者Akuma no Kagaku-sha), he is the infamous creator of the Build Driver, the Fullbottles, the Sclash Driver, the Sclashjellies and the Transteam system.