Daichi has a close relationship with Sugawara, having been friends since their first years. They know each other very well and rely on each another as teammates and friends as they've been through the ups and downs of their team together. Along with Asahi, they often hang out together outside of the team. Sugawara also seems to be the only member of Karasuno who can lecture Daichi and occasionally be immune to his intimidation.
Daichi has a close relationship with Karasuno's ace spiker and enjoys teasing him. Along with Sugawara, they've been through the ups and downs of their team together since joining together in their first year. They often hang out with one another outside of team activities. Daichi believes in Asahi's abilities and commitment, even trusting him to return to the team despite Asahi's reluctant attitude at that time. Because of this and Daichi's general reassuring disposition, Asahi respects Daichi as a teammate and captain.
Daichi went to the same junior high as Ikejiri and they were on the volleyball team together. Ikejiri was inspired by Daichi back then because of his unwavering determination in winning a match despite the huge probability of their team losing. Even now, nearly three years since they last saw each other, Ikejiri still remembers Daichi's quote, "We'll never win if we don't believe we can." They apparently lost contact after graduating junior high, but after their teams went up against each other in the Interhigh, they've become close again and see each other more often. After Interhigh, Ikejiri is shown to support Daichi by giving encouragements to him and cheering on Karasuno in its matches.
Daichi is close to Kiyoko as he was the one who recruited her into Karasuno in their first year. They occasionally talk to each other outside of team activities. Daichi also finds her attractive.
First Years: Daichi initially threw out Kageyama and Hinata because of their antagonistic relationship, but this was later revealed to be part of a plan to get the two to collaborate to form an incredible attack pair for Karasuno. He believes in the two's abilities and cares a lot for them, but often has to break up their arguments. Daichi cares about Tsukishima as well, but didn't know how to help him overcome his lack of passion towards volleyball. In the end, he's glad that Tsukishima was able to work it out himself.