Hokuto Hayasugi holds a pivotal role at the Shinkansen Ultra Evolution Institute (SUEI), advancing from director of the Ōmiya Branch to leadership in Kyoto. He pioneers the Ultra Evolution Speed theory and spearheads the ALFA-X prototype, a Shinkalion engineered to interface with future pilots. Its accelerated development, driven by an extraterrestrial menace, integrated enigmatic data from the future. During an invasion crisis, a nine-year-old Hokuto—displaced from his timeline by Valhallan Glowing Particles—temporarily assumes ALFA-X’s controls, deploying Rolling Stock Blades and Railway Crossing Shuriken against alien forces before reuniting with his era.

Privately introverted yet deeply passionate about Shinkansen trains since childhood, adult Hokuto adopts an exuberant demeanor, frequently baffling peers with rail-themed metaphors. He balances professional rigor with devotion to his wife Sakura and children Hayato and Haruka. The death of colleague Chikuma Kiyosu intensified his resolve in SUEI’s missions, especially when family safety is at stake, though his morning tardiness consistently tests Sakura’s patience.

Uniquely, Hokuto operates the Shinkalion 500 Kodama at peak efficiency as its sole adult pilot—a feat achievable through the unit’s intrinsic design rather than personal compatibility. His career intertwines with mentoring figures like Shinpei Izumi, a former classmate turned superior, while navigating SUEI’s intricate organizational politics.

The younger Hokuto’s temporary alliance with ALFA-X highlights his adaptability and unwavering drive to safeguard others, mirroring traits carried into adulthood. His name, "Hayasugi" (meaning "too fast") and "Hokuto" (inspired by a Hokkaido express train), underscores thematic ties to rail culture. Across manga and anime iterations, his narrative weaves familial bonds, professional legacy, and growth, with visual and contextual distinctions between adaptations reflecting his multidimensional impact.