Dr. Shizuma de Montalban III revolutionized global energy by inventing the Shizuma Drive, a clean power system that replaced nuclear and fossil fuels, ending energy crises and pollution. He co-created it with four other scientists, including colleague Professor Franken von Vogler.

A decade before the main events, an untested activation of the drive caused the "Tragedy of Bashtarle," shattering the nation and triggering the "Still Energy Phenomenon." This global energy failure claimed two-thirds of the world's population. Official records falsely blamed von Vogler for recklessly initiating the test. Only Dr. Shizuma and the other surviving scientists knew the truth: the four others, himself included, proceeded against von Vogler's cautions. They concealed their actions to protect their reputations and ensure the drive's completion, scapegoating von Vogler.

Dr. Shizuma carried profound guilt over the cover-up and von Vogler's death, manifesting as intense paranoia and hallucinations of von Vogler as a spectral pursuer. He possessed one of three anti-drive samples capable of neutralizing Shizuma Drive energy. When Big Fire attempted to steal this sample, he became a target. Pursued by Big Fire operatives across Shanghai and later Nanjing, he was temporarily rescued by the Experts of Justice but assassinated by Big Fire agents shortly afterward. His death occurred before he could reveal the full truth about Bashtarle.

He is the father of Genya and Ginrei. Genya, believing his father's dying wish was for revenge, joined Big Fire. Ginrei honored Dr. Shizuma's legacy by supporting the Shizuma Drive's ideals through the Experts of Justice. Dr. Shizuma's scientific legacy was complicated by the eventual revelation that the Shizuma Drive had a critical flaw only von Vogler's research could resolve, forcing Genya and others to confront the true nature of his work. His actions and the cover-up indirectly fueled the central conflict between the Experts of Justice and Big Fire.