Gou Hibiki, initially named Go Hibiki in Japanese media, steps into the racing world as the younger brother of Kenichi Hibiki—a driver and engineer presumed dead during a Mach 5 prototype test. After the tragedy, their father Daisuke retrofits the car with cutting-edge safeguards labeled “Safety Seven” and an experimental “X” engine, entrusting Gou to uphold his brother’s legacy by competing in the Grand Prix. Gou’s journey unfolds through two distinct arcs. The first pits him against corporate espionage, rival racers, and fragmented clues about Kenichi’s accident. Amid these challenges, the enigmatic Masked Racer—later revealed as Kenichi operating under the alias Racer X—emerges to shield Gou from adversaries like the Exelion Corporation. Their fractured bond fuels tension between Gou’s racing ambitions and Kenichi’s shadowy mission to dismantle racing-world corruption. A pivotal “Mirage Shot” event triggers the second arc: achieving 555 km/h in the Mach 5 propels Gou and allies into 2555, a future ruled by Handler, an alien warlord hunting the Ezekiel Wheel—a time-manipulating energy source. This shift redefines Gou’s role from circuit competitor to guardian of temporal integrity, merging high-speed races with clashes across dimensions. Central relationships anchor his story: investigative reporter Mai Kazami aids his quests, while her brother Wataru evolves into a steadfast companion. Family ties remain pivotal, particularly Gou’s unresolved grief over Kenichi’s absence and the weight of his father’s engineering legacy. A baby gorilla named Rocky, replacing the original chimpanzee, adds levity to their crew. Though defined by tenacity and loyalty, Gou’s resilience is strained by narrative shifts from gritty motorsport rivalries to battles against extraterrestrial domination. Unanswered questions linger—Kenichi’s dual identity, the Mach 5’s latent capabilities—positioning Gou as a linchpin between his family’s history and a fractured, multiverse-spanning horizon.