Imaizumi was the first cyclist to stumble upon Onoda, who was easily riding his mommy bike up the "back-gate hill" at Sohoku High, and was shocked to see him casually singing while doing so. Because of this, he challenges Onoda to a race, and as motivation, promises that he will join the Anime Club Onoda plans to revive if he loses. Imaizumi ends up winning, but Onoda pushed him to use his dancing technique in order to beat him. After Onoda reveals one of his main motivations for the Anime Club is that he doesn't have any friends, it remained on Imaizumi's mind. When Onoda came to see him the next day Imaizumi suggests that Onoda join the bicycle racing club, which he will be doing so himself next week, although he clarifies it's just a suggestion, and though Onoda has potential, he can only truly ride and succeed if he wants it for himself. Imaizumi even stated that he tried talking to those attending Sohoku from his middle school that he felt might be interested in the Anime Club, and wished Onoda luck with it.
Onoda admires and respects Imaizumi, surprising others when he calls Imaizumi a "nice person." During the earlier part of the series, being able to reach Imaizumi's level of skill was one of the main reasons Onoda trained so hard to become a better cyclist. While it may seem to the casual observer that it would be unlikely that the two could become friends, after being repeatedly surprised by Onoda's accomplishments (most notably when Onoda wins King of the Mountains title during in the First Year Welcome Race), Imaizumi seems to develop a fondness towards Onoda.
According to the bonus clips at the end of each episode of the anime, Imaizumi is shown to develop a liking to Love Hime; he even goes to see the movie and attends an anime convention with Onoda.
Naruko met Onoda during his first visit to Akihabara. Naruko immediately recognizes Onoda as an otaku and asks him for advice about what figures to purchase. However, he ignores Onoda's advice and buys the figure that looks the coolest, which put 1000 yen short and so he asks Onoda for a loan. Once they leave the store, Onoda thinks that Naruko is the kind of friend he would like to go to Akihabara with, although initially Naruko keeps mispronouncing his name as Onoda couldn't speak to him properly at first. Later, a man insults Onoda's city bike and Naruko convinces Onoda to chase the man down together on their bikes by riding quickly on the road - something Onoda had never done before. Naruko also taught him how to use his new front deraileurs to shift gears, and he was surprised by Onoda's speed. This is the first time that Onoda rode cooperatively with another cyclist when Naruko pulled for him, then pushed him to get to the car. But while Onoda overtook the car, he forgot to return the cigarette butt.
The next day Naruko is quite pleased to discover that he and Onoda are attending the same school. Afterwards, like Imaizumi, Naruko suggests that Onoda should join the cycling club. As the series progresses, they become incredibly close friends and Naruko ends up as something like a brother figure to Onoda.
In season 3, after Naruko loses the race to Midousuji in Osaka, Naruko starts practising climbing and pulling Onoda on hills, Onoda has noticed he takes practises a lot more seriously. But he has passed on advice on how to become a senior to the first years, as Onoda never stayed in a club, if at all, for a second year, though Onoda needed help from others to help him actually be a good senior by shaking every first years' hands.
Makishima acts as a mentor figure to Onoda, often giving him advice on bike racing. At first, when Makishima saw Onoda race with the other first-years, he didn't believe that Onoda could catch up to others or even reach the mountain peak before Imaizumi. He was proven wrong when Onoda won, making him hopeful that the club just may have found another climber. Makishima's first real conversation with Onoda during one-on-one training was awkward, and Makishima came right out and said that he is bad at socializing. Makishima told Onoda not to copy his dancing technique, a warning which Onoda promptly ignored. Onoda decided to try anyway only because he thought it was cool, not because he had any belief that doing so would make him a better climber, and though he was not very successful at copying Makishima's style he did become proficient at dancing. After that practice session, Makishima met privately with Kinjou and expressed his certainty that Onoda had the potential to be a fellow climber whom they could train, a prospect which excited him greatly.
Makishima began to warm up to Onoda, even asking Kinjou to thank Onoda for him during the Inter High. Onoda looks up to Makishima a lot; he later tells Teshima that he thinks Makishima is the "fastest and coolest" climber in the world. After the Inter High, when Onoda takes the team to Akihabara as leader of club activities for the day, he buys Makishima the most gifts to show his appreciation for all Makishima has done for him: ten Kumotaro keychains from Mogu-Mogurinko, a spider character. For the same reason, in Omake 17, Onoda copied Makishima's habit of wrapping his hair into a turban-like shape for drying, which was only partially successful because his hair was too short, so he couldn't tuck the hair near the nape of his neck.
In the beginning of season 3 in the anime, Onoda received tips on dealing with his new and lighter bike from Makishima. After initially rejecting riding with him up Mt. Minegayama, he went again because he got a bad feeling. They raced to the top, but Makishima beat him again.
Onoda became depressed upon hearing of Makishima's departure for England, which caused him to be in a slump as he began to do poorly in practice and races. He is shown to be struggling with his sadness over Makishima leaving, and fulfilling his request to take care of Sohoku and to become stronger. It's only by watching Hakone's ace, Ashikiba Takuto "Metronome Dancing", which reminded Onoda of Makishima's dancing, that he's able to get over his slump.
Some time after Makishima left for London, Onoda started writing letters and training reports to him, though Teshima suggested that he doesn't write too much, because he hardly ever writes back, and only replies in a few words if he does, even when asking for tutoring help in Mathematics.
As Kinjou is the captain of the team and a talented cyclist, Onoda has a lot of respect for him. Kinjou also has a lot of faith in Onoda due to his determination and unpredictable successes, talents that Onoda shows off when he manages to catch up to the others after being caught up in a crash. Kinjou is supportive of Onoda and praises his accomplishments. Onoda is shown to take the tasks Kinjou assigns him to heart.
Just as he does with the other third years, Onoda has respect for Tadokoro. During the second day of the Inter High, Onoda argues with Makishima to gain his permission so he can wait for Tadokoro to catch up with him. Tadokoro had been losing heart in the absence of his teammates, but after the initial anger he felt at Onoda falling behind with him, he developed respect for Onoda. Despite Onoda's small stature and odd behavior, he was able to bring Tadokoro back to the group 70 km later, drafting him the entire way. Tadokoro even agreed to sing an embarrassing anime song because it allowed Onoda to ride confidently. He is very grateful to Onoda afterwards, and Onoda is happy that Tadokoro agreed that riding together while singing was fun. As a result, Onoda gave him the Love Hime Theme Song CD after the Inter High at Akihabara.
Miki was very friendly towards Onoda during their first meeting, which makes Onoda think that even people from sports clubs can be nice. She even does research to find out about him because she was curious about his cycling. She often talks to him during school, which Onoda is both embarrassed about and appreciative of. Miki is the one who corrects Onoda's saddle position during his first race with Imaizumi, and gives him a double gear front deraileur as well as supplies him with a road racer later on. She constantly cheers Onoda on during races and is amazed at his rapid progression as a cyclist. Onoda does not have any overt romantic intentions toward Miki, but does consider her attractive and when he thought of her during Training Camp, unconsciously blushed. While Onoda continues to be easily flustered around her, the two can certainly be considered friends.
Onoda and Manami have mutual respect for one another. The two first meet when Onoda is left behind on the side of the road to recover from carsickness until he's picked up. Manami discovers him and offers Onoda some water, which Onoda accepts gratefully. He asks Onoda if he likes slopes, one of Manami's favorite things, and Onoda replies that he does. Manami is late for school, so he continues on his way, leaving his water bottle with Onoda. They meet again and bond during the third day of Sohoku's training camp when Manami arrives to scout for Hakone Academy but mistakes the "strange climber" he heard of for Onoda instead. They have a small race that Manami wins. Manami then makes a somewhat one-sided promise that they should meet at the Inter High; there, Onoda should return the water bottle Manami let him borrow. They are excited to see and compete with each other at the Inter High. Aside for their respect for each other, they share a friendly rivalry due to their positions as first year climbers on opposing teams. Also, when Manami lost the final race to Onoda, he again hoped that both of them will return to compete next year.
Onoda encounters Midousuji on the first day of the Inter High when he has to pass 100 people to catch up to his team. Midousuji is that 100th person, and Onoda recognizes that Midousuji is strong, but he is still determined to pass him. Midousuji challenges Onoda before falling back when Onoda passes him, though of course he still considers himself superior. Midousuji decides that Onoda isn't just your average, "mass-produced" cyclist. Onoda considers Midousuji "a good person" because he was the only one in the series who answered Onoda's question about anime (a Gundam series reference). Even though the two of them have different goals, Onoda feels a sympathy towards Midousuji.
During the third day of the Inter High, Onoda, Arakita, and Manami get left behind in the pack. The three of them end up working together in order to catch up with their teams. Onoda persistently asked Arakita to ride with him, even though he said that Arakita is the type he is "weak against." Despite their conflicting personalities, the two developed a relationship built on mutual respect. Arakita begins calling Onoda "Onoda-chan" and Onoda thinks that Arakita is 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. Onoda is quite distressed when Arakita drops out of the race later. Onoda is still utterly terrified of him.
Shortly after the third years stop attending club, Sadatoki comes to visit Sohoku's cycling team. Onoda is initially somewhat disappointed when Sadatoki shatters his dreams of being a senpai to an idealized kouhai but is flustered and pleased when Sadatoki praises Onoda's strength and talent. Sadatoki says he wants to be like Onoda, and is able to replicate his high cadence for a short amount of time while riding together.