Fukutomi Juichi
Arakita and Fukutomi had a disastrous first meeting, as Arakita insulted Fukutomi and even physically assaulted him. After losing a race on his moped against Fukutomi and joining the cycling team, Arakita later came to respect him, saying that Fukutomi is the only one he "acknowledges." This respect goes so far that Arakita does not become physically violent anymore nor pick fights simply by Fukutomi's orders. His loss to Fukutomi is what caused him to develop an interest in bicycles, and Fukutomi is the one who encouraged him to move forward in his life (very literally telling him that the only way to successfully ride his bike was to "look forward" and relinquish all past ties). Over the years, the two developed a more friendly relationship, and Arakita often works as an assist to Fukutomi during races. In the past, Arakita called Fukutomi "Iron Mask" (tekkamen), stone-face, but he currently has a nicer nickname for him: "Fuku-chan."
Shinkai Hayato
Shinkai was one of the club members initially interested in reaching out to Arakita when he first joined, curious about why Arakita rode, and quickly started calling him by his first name. His easygoing personality seems to mesh well with Arakita's aggressive one. Drama CDs and post-credits scenes of the anime frequently depict Arakita hanging out with him and other members outside of club activities. Shinkai does not react negatively to Arakita's constant complaining and insults, as with the loss at the Sprinters Checkpoint on the second day of the Inter High where Arakita pulls him along afterwards, complaining about being tired and calling Shinkai uncool for losing despite his confidence; rather than being affronted, Shinkai thanks him for allowing him to recover. Shinkai knows that Arakita is truly soft under his abrasive nature, and can easily manipulate this when he wants. On at least one occasion, Shinkai resorted to crying rivers of faux tears when Arakita refused to try the food he was enjoying, which successfully guilted Arakita into eating it. He's also gotten Arakita interested in reading mystery novels instead of just manga, and allows him to copy his homework (even though it appears the answers are usually all wrong).
Toudou Jinpachi
Initially, Arakita didn't get along well with Toudou in the slightest. After Toudou tried to be friendly when Arakita first joined the club, Arakita simply insulted his hairstyle and refused to tell Toudou about his past athletic experience, which Toudou could tell must have existed. Although he instantly understood Arakita probably had bad memories about his past, Toudou was insulted by the headband comment to the point that he wanted Arakita to quit the club. Over time, though Toudou claims he never thought they'd be riding together, the two grew to highly respect each other as cyclists. As third years, they tend to bicker, but usually over trivial things like Toudou scolding Arakita for trying to copy homework or his eating of unhealthy food, and when Arakita insults Toudou for not knowing something, Toudou is quick to study up on it out of spite. They seem friendly enough towards each other regardless of how they clash; In extra material, Arakita has called Toudou to wish him happy birthday and offered to buy him a soda. (Unfortunately, he mistakenly called someone else.) Watanabe said that Arakita would be the first to text Toudou "Happy Birthday" despite how he acts, because that's the sort of guy he is. At one point, Toudou, after Arakita berates him for being terrible at handling cats, doesn't hesitate to cuddle Arakita like a cat to demonstrate his newly-learned cat appreciation techniques.[1]
Onoda Sakamichi
During the third day of the Inter High, Arakita, Onoda, and Manami get left behind in the pack. The three of them end up working together in order to catch up with their teams. At first, Arakita did not want to team up with Onoda, but the latter's persistence in asking payed off. Despite their conflicting personalities, the two developed a relationship built on mutual respect. Arakita begins calling Onoda "Onoda-chan" and Onoda calls Arakita an "amazing person." Once they return to their teams, Arakita tells Onoda that they have returned to being opponents, and therefore Onoda should not thank him. Later, Onoda is distraught when Arakita drops out of the race.
Machimiya Eikichi
Although Machimiya initially detests Arakita for being part of Hakone Academy, taunting and violently headbutting him during their battle at the Inter High to the point of drawing blood, Arakita says that he doesn't hate Machimiya's type and that Machimiya resembles his past self. This prompts him to tell the story of when he first began cycling and how he learned to move forward. Arakita wins their battle and offers to buy Machimiya a Bepsi after the race. Machimiya accepts his loss to Arakita with surprising grace considering how hard and dirty he fought, and looks forward to that Bepsi, coming to admire Arakita and his cycling. By the time Arakita actually buys him Bepsi after the Kumamoto Race, it fizzes all over Machimiya's face. In the 3DS game, Machimiya follows Arakita to Hakone Academy's training camp with Sohoku in order to race Arakita again and repay him for that Bepsi. Watanabe has said that Machimiya attends Yonan University with Arakita and Kinjou after graduating high school.
Kuroda Yukinari
Arakita and Kuroda's first meeting almost ended in a fistfight, but Arakita held back because Fukutomi helped reform his behavior. Arakita told Kuroda that, despite his athleticism, he was not cut out for cycling. Of course, this was a great insult to Kuroda, who succeeded at every other sport, especially baseball, where Arakita's own baseball path is cut short. Kuroda later came to respect Arakita a great deal, and it appears that Arakita thinks Kuroda has become quite skilled.
Kinjou Shingo
Second Year Events
Arakita and Kinjou later attend the same university. While of course Arakita retains his confrontational personality, the two seem to get along well enough. Arakita is seen speaking to Kinjou in class, asking about the condition of the new Sohoku and mentioning the strength of the new Hakone Academy team.