On the second day of the previous Inter High, which took place in Machimiya's hometown of Hiroshima, he encountered some unforeseen trouble when both of his water bottles broke open. He then happened upon Fukutomi Juichi and asked if Fukutomi could lend him a water bottle. Fukutomi declined Machimiya's request and Machimiya performed poorly during that day's race, with Hakone Academy sweeping the podium on Day 2. He blamed Fukutomi for his troubles and developed a grudge. However, Machimiya managed to place third overall at that Inter High, where he passed three riders suffering various issues in the final 3km of the third day.
Machimiya wears the bib number 31 at the next Inter High. Hiroshima never does well in the first two days of the Inter High, but Machimiya and his team are introduced on Day 3 prior to the start of the race, where he tries to flirt with Kanzaki Miki but fails, and threateningly touches and talks to the captains of Hakone Academy and Sohoku until he's chased off.
Machimiya gathers all the cyclists falling behind in the Inter High and uses their resentment against the top three schools as a chain to manipulate them all into riding as pack to swiftly reach the front. The mass of riders moves like a giant snake, swallowing up anyone in its path including members of Kyoto Fushimi and Kumamoto Daiichi. Taura Yoshiaki is unwilling to ride cooperatively with them, but after hearing Machimiya explain the benefits and the plot to take revenge on the top schools, he and his team ride with the pack. Fujiwara Masa, an injured Kumamoto climber, being brought to the center of the pack where there is no wind, to be nursed back to health, is one of the tactics Machimiya uses to convince Taura to join his cause.
When Onoda Sakamichi is swallowed by the pack, he meets Taura, who happily explains their plan to take the front. However, Taura, along with the other cyclists, has been deceived: Machimiya mocks him and the others for falling for his plot, and the entire Hiroshima team ditches the pack and rides ahead. Taura initially believes he's joking, and laughs, but ends up in tears once crushed with reality. With all the sprinters in the pack exhausted, as their pace had been too great, Taura and the other cyclists are left behind.
After Machimiya breaks away from the group, Onoda convinces Arakita Yasutomo, who was also caught, to chase him, which Manami Sangaku joins in on after Arakita yells at him for being caught too. They pass their teammates to reach Hiroshima and confront a shocked Machimiya; Arakita tells him "that's the look I wanted to see on your face!"
Unable to shake the three cyclists off, Machimiya and Ibitani Ryou challenge them to a race for the name of the champion as part of his grudge against Hakone Academy: if one team falls behind by three flags, they must cease pursuit. Though Fukutomi told Arakita to do what ever it takes to bring Manami back to the front should the boy fall behind, Arakita accepts the challenge, resulting in a fierce battle.
Machimiya taunts Arakita for calling Fukutomi "Fuku-chan," calling him a "domesticated pet wolf." During their race, Machimiya headbutts Arakita to the point of causing him to bleed. Despite the rough actions of his competition, Arakita smiles and says he knows how Machimiya feels because he used to be the same kind of person, filled with bitterness. This is the confrontation that prompts Arakita's flashback to when he first met Fukutomi, parts of which flashback appear earlier in the anime.
Arakita tells Machimiya that there's no way to move forward if he's hung up on the past, and that if he'd learn to move forward, he could've ridden with true heart and strength. Arakita pulls ahead of Hiroshima's team, and his parting words to Machimiya are that he'll treat him to a Bepsi later; after delivering this line, he pulls Manami and Onoda so far ahead that Machimiya accepts defeat. Ibitani tearfully wishes to pursue them and ignore the rules they previously set, as he knows Machimiya broke up with his girlfiend Kana to win the Inter High, but Machimiya stops him, saying that Arakita is right. He watches Arakita ride away, in awe of him.