Takahito Saionji commands the Mobile Rescue Police, handling complex disasters and emergencies with serious, practical leadership that earns widespread respect. He has short dark red hair featuring a distinctive messy front tuft, orange eyes, and wears a white shirt, red tie, grey vest, and green jacket bearing a gold "DH" badge on the sleeve.

As uncle and guardian to Drive Head driver Taiga Yagura, he shares a long-standing school friendship with Jou Kurumada, collaborating closely within their organization. He shows particular concern for colleague Arisa Munakata during her Synchro Fusion training.

In television episodes, Saionji oversees rescue operations and public relations, appearing on Akasaka TV to discuss Drive Head activities while protecting driver identities. During an oil plant inspection, an Evil AI traps him and president Maruyama in a fire; Taiga rescues them using the upgraded Brave Backdraft. He authorizes critical missions like deploying the Cyclone Interceptor's Hyper Shot Gun to save a sinking submarine. Investigating Black Chips and the Evil AI's origins, he reacts gravely to its plan to shift Earth's axis and eradicate humanity. He monitors the final battle against Ark alongside Kurumada from command.

The web series shows Saionji collaborating with Kurumada and drivers to implement Mk-III Drive Head upgrades.

In the film, he and the Mobile Rescue Police react with shock to a warning from presumed-dead Dr. Karigari about Terra. After Terra corrupts Drive Gears' Justice Circuits, he grounds child drivers and recruits temporary pilots from the Mobile Assault Police. He accompanies Gou Kurumada to investigate the Cyclone Interceptor's disappearance, urging caution despite Gou's trust in Karigari's modifications. Prioritizing civilians, he orders Munakata to halt attacks on Terra to rescue Kasumi Haruno from a compromised bus. With Kurumada, he observes Gou defeating Terra and saving Kasumi.

His name was localized as Won Jin Seo in the Korean adaptation.