Hokuto Hayasugi serves as a central figure displaced from his own time, arriving in the present as a nine-year-old child during an extraterrestrial invasion led by Nahane and Ohanefu. Facing this planetary crisis and the emergence of the advanced Shinkalion ALFA-X prototype, the Shinkansen Ultra Evolution Institute designates young Hokuto as its pilot out of necessity and potential high compatibility, despite his youth. This critical role positions him to lead a coordinated defense effort uniting Shinkalion teams from across Japan.

While details of his life before displacement remain unexplored within the movie, his known adult personality in the main series—marked by extensive train-related analogies—suggests a pre-existing enthusiasm for railways. His sudden arrival and immediate recruitment thrust him into immense responsibility during the emergency.

Personality-wise, this young Hokuto contrasts with his exuberant, railway-obsessed adult counterpart. As a child, he is quiet, reserved, intelligent, and prone to isolation. Nevertheless, he demonstrates significant adaptability and courage confronting the alien threat. His role is defined by this unexpected arrival, his pivotal assignment piloting the ALFA-X, and his contribution to uniting the Shinkalion defense against the space-borne invasion.