Kōtarō Suwa/Relationships

Suwa Squad
Suwa is the unifying force of his Squad, raising his teammates' morale. They have a good relationship and hang out together outside of Border duty. Despite his penchant for gambling in battle, Daichi Tsutsumi trusts Suwa, while Hisato Sasamori deeply respects him. All his teammates address Suwa by his surname, presumably as a sign of respect, although they speak casually to him and Rui Osano has no qualms about teasing him. On the other hand, Suwa calls at least Sasamori by his first name.

Sōya Kazama
Kazama and Suwa are the same age and part of the same group of friends, often going out eating and drinking together. On one such outing, Suwa got Kazama so drunk that the latter picked a fight with a postbox. For his part, Suwa is plotting revenge on Kazama for causing his name to become synonymous in Border with trion cubes. They address each other by surname.

Reiji Kizaki
Kazama, Kizaki, Suwa and Terashima are the same age and part of the same group of friends, often going out eating and drinking together. Suwa addresses Kizaki by his first name, without honorifics, implying closeness, and referred to him by an unflattering epithet ("beefcake gorilla") on at least one occasion.

Raizō Terashima
Kazama, Kizaki, Suwa, and Terashima are the same age and part of the same group of friends, often going out eating and drinking together.

Haruaki Azuma, Shinji Fuyushima and Kei Tachikawa
Suwa is mahjong buddies with Azuma, Fuyushima, Tachikawa, who gather to play in Suwa Squad's operation room. Suwa is very informal around Fuyushima, calling him "old man" while praising his usefulness during Galopoula's blitz.

Mitsuru Tokieda
Suwa and Tokieda seem to be on good terms. The two were seen walking and talking together in HQ.

Yūma Kuga
Suwa is very impressed with Yūma's skill and enjoys watching him fight. They seem to have grown close at some point after their Squads competed in a rank battle, since Yūma walked over to Suwa, Sasamori and Tokieda when he spotted them and let himself be playfully manhandled by the captain. Suwa refers to Yūma as the "albino shrimp".

Atsushi Hokari
Although the relationship between the two is unconfirmed, they might be on good terms since Suwa referred to Hokari by his nickname.

Kyōsuke Karasuma
Suwa addresses Karasuma by his first name without adding an honorific, which might suggest they are close.

Shun Midorikawa
Midorikawa appears to know Suwa, as he could anticipate how the captain would react to Tamakoma Second's map choice before their match. They both refer to the other by their surnames.

Osamu Mikumo
Suwa was annoyed with Osamu continuing to challenge Kazama after his 20th consecutive defeat, although he was so swept away by his ingenuity in the last fight that he ended up rooting for him.

Chika Amatori and Ai Kitora
Although he does not enjoy his name becoming synonymous with trion cubes, Suwa is relieved that it happened to him rather than Chika or Kitora.