Prior to high school, Naruko was still incredibly short for his age, easily mistaken for a kindergartner even though he was in his third year of elementary school. He first saw people riding road racers on his way home from an errand, and immediately fell in love with the thin and flashy look of the bikes. He got a red Pinarello and started riding right away, but couldn't produce results. Fellow cyclists made fun of him for his short stature and blamed that for his failure. Naruko promised himself that he'd become stronger and continued to ride even though he kept failing throughout elementary school and middle school. He hid his failed attempts at riding from his classmates. In the end, it took him five years to win anything.
A New School
Naruko's first appearance involves him searching around Akihabara for a place to buy gunpla for his younger brothers. It is clear from the beginning that he is bold, outgoing, and somewhat rude. He likes to stand out; red is his color of choice, from his hair to his clothes to his bike. When he runs into Onoda, he says that while Onoda's bike looks boring, it is a good one because Onoda puts his trust in it. Naruko reveals that he is from Osaka (as if his accent didn't make that obvious enough), a city well known for the cycling population and bike factories, and that his family recently moved to Tokyo. He is angered when a man flicks his cigarette butt on Onoda's bicycle, so he drags Onoda into biking to catch up to the man's car on their way home to Chiba.
Joining Sohoku's Cycling Team
After the Inter High
Onoda is assisted by Naruko and Imaizumi in explaining to his mother why he'd been racing at Mt. Fuji. She has no idea what they're talking about, so Naruko puts it simply that Onoda became the fastest person to climb Mt. Fuji and shows her a magazine article on him. After she laments how she didn't have a camera to take photos herself, they're all shocked to learn she was at the race. Before they leave the Onoda family's house, Onoda's mother tells them to be careful but keep working hard at cycling, and for Naruko and Imaizumi to take care of Onoda.
The first-years arrive to meet Sohoku's third-years on the road. Because he won the Inter High, Onoda leads the next practice, and takes the team to Akihabara. Naruko and Imaizumi can manage, but the third-years feel extremely out of place. Naruko witnesses as Onoda gives gifts to the third-years that they don't grasp. Onoda admits that they're all graduation as well as gratitude presents for the third-years for bringing him to the Inter High. Onoda thanks them all for their help in realizing his potential. Although previously confused at being in a strange place, the third-years accept the gifts.
While the team is distracted as Onoda explains things about Akihabara to Tadokoro, who mistook greeters for foreigners and argues with Naruko, as well as Onoda's questioning if the third-years will continue to attend practice, Imaizumi notices Makishima lagging behind; the team is unaware of Makishima's thoughts that despite his gratitude towards them, which can't be measured like Onoda's by the amount of gifts to one person, this is really farewell.
In the anime, Makishima's monologue is cut, as the team rides happily from Akihabara together, with Naruko and Imaizumi engaging in a race, knowing they will be the ones carrying the team along with Onoda.
The first-years all gain new equipment after the special trip to Akihabara, Naruko's being a new set of deep carbon wheels.
After the Hakone Academy third-years have completed their day at a theme park, they look over the photos taken earlier and are startled to see Onoda and Imaizumi racing on children's bikes in the background of one. Naruko is seen in the distance of the same photo. Behind them, team Sohoku (minus Makishima) rides on a multi-person bike, with Kinjou running behind them, shouting about how Sohoku never gives up.
As sprinters, Tadokoro, Naruko, Aoyagi and Sugimoto participate in the Road Race Season between March and November, the final race is the Bay Coastline Criterion, a 10 lap race around a closed field. While Sugimoto leads the peloton (chasing pack or platoon), the other Sohoku riders broke away and attacked individually in the final three laps, with Tadokoro winning the race in the final 10m, ahead of Naruko and Aoyagi. Though Naruko was unhappy that he has lost in what was to be the final sprint battle with Tadokoro, both Naruko and Aoyagi bowed to him in gratitude after the medal ceremony, before they both punched Tadokoro's kidneys.
The day after, Naruko wore a costume and mask, riding on Naruko's own bike on rollers to imitate Tadokoro Jin.
Return to Osaka, switch to All-Rounder
After Shoreline Criterion, Imaizumi suggested him to become an all-rounder as he has seen Naruko had shown glimpses of his climbing skills (the same idea Tadokoro suggested last year because he is much lighter than Tadokoro, and is better suited to climb), but Naruko needed time to reflect, so he took time off to return to Osaka and his home track near the port. He had beaten Handai High School's Kakimoto Ryudai and Daitsubu Takeshi in two 3-lap sprint races, but he lost to Midousuji in the final gauntlet, a 10-lap 6km race, hence he has to give up being a pure sprinter. He returned to Sohoku at night, dejected, and silently went into the sheds after sending Onoda fried octopus balls, one of Osaka's famous treats.