When he was younger, Tadokoro came in last at the Minegayama Race and lost to beginner cyclists in middle school. He dropped out of a training camp on the second day. Because of his large body, he was unable to perform well on climbs. Frustrated that not eating depleted his strength and at his inability to lose weight, Tadokoro wanted to resign from Sohoku's bicycle club after placing last in the First-Year Welcome Race. He still enjoyed cycling, but thought it was pointless to continue riding if he could never win. However, the captain at the time, Kanzaki Tooji, told him that quitting was fine only if someone didn't mind losing, not if that person wanted to win. He encouraged Tadokoro to become a sprinter in order to become good at one thing and to worry about the other later.
During training afterward, Mr. Pierre drove Tooji by Tadokoro's side as he pedaled. When Tadokoro claimed he couldn't pedal anymore, being at his limit, Tooji replied that a person decides their own limits, and that Tadokoro needed to decide with his heart, not to let it be weaker than anyone else's. Tadokoro embraced these words and continued to push himself further as Tooji instructed him on how to sprint.
Mr. Pierre states that Tadokoro made a breakthrough from this. Tooji said it was for the best that sprinters be simple and straightforward, and that Tadokoro had guts even though he would probably lose over and over. He believed Tadokoro would just keep moving forward, even if he fell or became dirty, until he won and his perspective of the world would change. To him, a sprinter who doesn't know loss can never become stronger. Tooji, visibly wearing a sort of brace on his left knee, thought that Tadokoro would become a good sprinter if he trained hard enough with his instruction, and would carry on the captain's will—although Tooji claimed the latter was a joke.
At the Inter High, after Fukutomi Juichi caused himself and Kinjou Shingo to crash, Tadokoro witnessed Kinjou struggling as he crossed the finish line. Once the Sohoku members found Kinjou at the goal, Fukutomi appeared and apologized to all of them, explaining what happened was not quite an accident. Fukutomi blamed his actions on his weakness. Tadokoro punched him hard enough to knock him off his feet. Fukutomi merely apologized again and stated that he made the decision to withdraw from the third day's race, even though he knew it wouldn't amount to anything. Tadokoro continued to shout at him, accusing Hakone Academy of using dirty tricks to win, and exclaimed that other teams aren't blessed with several aces like Hakone Academy. Both end up in tears. Surprisingly, Kinjou told Tadokoro to calm himself because nothing could change the results, and they needed to perform maintenance on his bike and get proper rest, heavily implying that he would still race the next day despite his injuries. Tadokoro relented and begun to walk away with his team. Fukutomi questioned Kinjou, to which Kinjou replied that as cyclists, they settle things only on the road, and no one knows who will win until the very end. Kinjou indeed raced the third day while Fukutomi did not, but Sohoku was still beaten by Hakone Academy, who took first place.
A month afterward, Tadokoro was still enraged at Hakone Academy. Fukutomi still deeply regretted his actions and visited Sohoku High to formally apologize, bringing manjuu ("Hakone Specialty steamed buns") along as a gift. This was despite Toudou Jinpachi's best efforts to warn Makishima Yusuke through a phone call, thinking Fukutomi had left to pick a fight. He had apparently left a note saying he was skipping practice to go to Chiba. As soon as Kinjou entered the club room, Fukutomi was directly behind him. The ensuing attempts to hide Fukutomi from Kinjou ended up with a stack of wheels ("accidentally", as Tadokoro put it) falling on the newly-appointed Hakone captain.
As Fukutomi apologized, he acknowledged that his actions ruined the efforts of Sohoku's entire team, revealing that he'd undergone a change in his philosophy. After this formal apology and reconciliation with Kinjou, Tadokoro seemed to rethink his opinion of Fukutomi and forgive him.
Building Sohoku's Cycling Team
At the end of the day, both Makishima and Tadokoro were very laid-back after losing to Fukutomi,which bothered Naruko greatly, but after Makishima "stepped out of his comfort zone", and explained in detail how half the field would be unable to race on Day 3 by disqualification (timed out), it changed Naruko's perspective greatly.
After the Inter High
After explaining to Onoda's mother what the Inter High was, 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. The third-years, including Tadokoro, feel extremely out of place. Onoda gives each third-year a gift. He gives a Love Hime theme song CD to Tadokoro, who is surprised that he had been singing such a song and knows so much of the lyrics. 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 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 inner monologue is cut, and the team rides happily from Akihabara together.
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. 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.