Tanaka gets along well with his older sister. Saeko cooks him dinner and would sometimes offer help with his studies, though he often declines. Since the beginning the of Spring High Preliminaries, Saeko has attended most of Tanaka's matches. She often cheers him on loudly from the bleachers.
The duo are shown to be good friends due to their similar rowdy personalities. Whenever they're excited, they tend to shout or celebrate excessively, much at the annoyance of Daichi. Tanaka and Nishinoya both have a soft spot for Shimizu and often band together to keep other boys away from her. They also hate guys like Oikawa for getting more attention from girls.
Tanaka and Yamamoto have similar looks and personalities: they're both loud and delinquent-like. At their very first meeting, they didn't get along well and almost fought. However, after the match Yamamoto approached Tanaka and admitted that he likes Shimizu, causing the two to bond over their crush. They even cried and shook hands as two were separating. Since then they've exchanged numbers to become text buddies; Yamamoto once texted Tanaka for advice on how to talk to girls. During the summer camp, Tanaka hung out with Yamamoto and, together with Nishinoya, even formed a team with him during the barbeque to keep away other players from approaching Kiyoko.