He has a close bond with Teshima to the point that Teshima can assume what he is thinking. The two met in their first year of high school (on the very first day, in fact) and have trained together as a team so that they could enter the Inter High together. Since they were both "average cyclists" on their own, they decided to work together in order to surpass their limits. They put in a lot of practice and spent time coming up with strategies, and their hard work paid off when Teshima managed to help Aoyagi be victorious in five out of six races. Though Aoyagi felt guilty about being the only one to get the prize, for Teshima it was satisfying enough to defeat "elite" cyclists. Aoyagi calls Teshima by his first name, Junta.
Second Year Events
Aoyagi cares about Teshima a lot, a fact illustrated by how Aoyagi worried about Teshima during his race against Koga. While the new Sohoku captain didn't seem to be bothered by his condition or the possibility of losing, Aoyagi says to himself that he's scared to go in the Inter High without Teshima. When Teshima passes by in front of the team during the race, Aoyagi is the only one of the club who cheers for him and screams "WIN!" When Teshima eventually wins, Aoyagi immediately rides to him while crying with happiness. Aoyagi thinks that Teshima deserved to win and that Teshima achieved victory by himself, without any help. However, this is not what Teshima believes at all. While racing against Koga, Teshima thought that he is able to win only because there is someone out there who believes in him. Even when they are not riding together, Aoyagi is an important mental support for Teshima. At the start of the 42nd Summer Inter High, Aoyagi helps Teshima calm down and the two prepare themselves for their first and last Inter High competition.
Aoyagi greatly admires Tadokoro Jin, whom he sees as a mentor. In Aoyagi and Teshima's first year, Tadokoro is seen supporting them even as they struggled to improve. It's the possibility of riding alongside Tadokoro in the Inter High that drives Aoyagi and Teshima to compete for spots on the team. Like Teshima, Aoyagi has the deep desire to make Tadokoro proud, and is devastated and ashamed when the two of them they lose to the first years, tearfully apologizing to Tadokoro for their failure while he comforts them. As they are both sprinters, the two often train and race together.
In his third year, Aoyagi takes on some of Tadokoro's defining traits; he creates his own version of Tadokoro's cycling style and even eats like him. When he comforts Onoda at the beginning of the Interhigh, he talks about how much Tadokoro has taught him, in manners both related and unrelated to cycling, such as eating and etiquette.
Second Year Events
When Onoda reveals that their former senpai are at the Inter High, Aoyagi seems excited by the possibility of seeing Tadokoro in particular.
It's revealed on the second day of the 42nd Inter High that, some time before Tadokoro's graduation, he gave Aoyagi the Love Hime CD he bought in Akiba, telling Aoyagi that since the song helped him during the Inter High, he might be able to find some use for it as well.
Second Year Events
When Teshima sends Aoyagi and Kaburagi out to take the sprinter checkpoint on the first day of the 42nd Summer Inter-High, they learn that Kaburagi still does not consider himself a sprinter. Ignoring Kaburagi's protests, Aoyagi grabs him and pulls him along. When Kaburagi is rude to other, older cyclists, Aoyagi apologizes to them. Aoyagi appears continually surprised at Kaburagi's mistakes, such as when the latter reads zekken incorrectly, and being completely unaware that he was using the lower handlebars when Aoyagi was pulling him before. When they face Doubashi, Aoyagi feels threatened but is at a loss when Kaburagi does not seem affected at all. Despite all this, Aoyagi thinks that Kaburagi has great potential as a sprinter, and even imagines introducing him to Tadokoro. Aoyagi even acted a "God of Orangena" to drop advice for Issa, given his superstitious nature. It is only then that he subconsciously follows the same pieces of advice that Imaizumi and Naruko tried to suggest to him.