Kengo Ino

This unnamed member of Blood Tribe, who transforms into Kamen Rider Blood by inserting the Great Cross-Z Dragon loaded in the Cobra Lost Bottle into his Build Driver, is the main antagonists of the Kamen Rider Build: Be the One film. He is one of Evolt's cohorts and a member of the conspiracy behind the Japanese Civil War.

Blood was originally one of the four members of the Blood Tribe involved with the destruction of all life on Mars who were sealed away by the Martian Queen Vernage within the Pandora's Box. After the Pandora's Box was unearthed on Mars by a team of four astronauts, Blood possessed the astronaut Kengo Ino and was able to travel to Earth alongside the other three members of his kind.

After Japan was split in three by the Skywall Disaster, Kengo Ino rose to become a prominent adviser to the Prime Minister of Seito, Masakuni Mido, driving him to engage in hostilities with the other two regions.

After the unification of Japan, Blood became one of the new governors of the three regions alongside his fellow Blood Tribe members Ryoka Saiga and Mitsuomi Gohara. The three would then enact their own plan to destroy Earth in the stead of Evolt, who abandoned their cause of destroying it in order to pursue his own goals.

He is portrayed by Masanobu Katsumura.