Itsuki Takeuchi stands as the protagonist’s boisterous confidant, balancing camaraderie with comic antics fueled by his hyperactive energy and occasional lack of filter. Between pumping gas at a local station and daydreaming about asphalt glory, he obsesses over street racing, determined to earn a spot in the Akina SpeedStars. A misguided purchase of a Toyota AE85 Levin—confused for its AE86 sibling—shatters his confidence, drawing ridicule until a friend’s adept driving proves the car’s hidden strengths, reshaping his belief in skill over machinery.

His bond with the protagonist traces back to middle school, forged in shared grease-stained hours at work and a mutual automotive fascination. Though his racing ambitions outpace his talent, he gradually sheds his naive bravado, confronting harsh realities after a reckless clash with rival Shingo Shoji spirals into a wreck, a hospital stay, and the collapse of his first romance. Later, a fleeting connection with Saitama-born Kazumi crumbles under her ex’s interference, compounding his heartache.

Unshakably optimistic, Itsuki masks vulnerabilities with jokes and idolizes seasoned racers, yet scorns front-wheel drives, automatics, and diesel engines with purist fervor. He wears the mantle of "Lonely Driver" after repeated romantic stumbles, though his friendships endure.

Years later, he anchors himself in Shibukawa, trading gas nozzles for charging cables while raising a family—a testament to maturity tempered by nostalgia for racing days. Beyond laughter, he nudges peers toward self-reflection, whether defusing tensions or championing focus behind the wheel, his legacy echoing both humble growth and enduring petrolhead spirit.