Noboru Koarai/Relationships

Tsuneyuki Okudera
Koarai and Okudera are teammates who seem to enjoy a good relationship and a friendly rivalry when discussing strategy in the presence of Azuma. Due to their differing personalities, Okudera may end up in some of Koarai's more reckless tendencies, and may feel frustrated when Koarai acts smug around him. This however does not diminish the concern Koarai shows for Okudera in combat, and the latter has also demonstrated to care about Koarai's mood. They address each other by surname, without honorifics.

Haruaki Azuma
Azuma is Koarai's captain and mentor. He educates him in strategy while giving him the space to come up with his own plans. In addition, he is to an extent responsible for Koarai's Trigger Set, having forbidden him to equip Sub Triggers until he showed to have grown enough. Koarai greatly respects Azuma and is filled with pride when validated by him. His admiration dates to before he joined Azuma Unit, as he clung to the captain's leg and begged for the chance to be part of it. They address each other by surname, with Koarai adding the honorific -san.

Mako Hitomi
Hitomi is a big sister figure to Koarai and Okudera, who joined Border when she did, and she may invite them to cool down when their discussions turn into ego battles. He has grown accustomed to finding her giggling while watching horror movies in the dark in the strategy room. Koarai calls her by name, to which he appends the honorific -san, while she uses his nickname without honorifics.

Taichi Betsuyaku
Betsuyaku is school friends with Koarai, whom he refers to by the nickname "Koala", without honorifics, seemingly connoting a rather close relationship.

Ken Satori
Koarai and Satori are school friends.

Hisato Sasamori
Koarai and Sasamori are of an age and might be close, seeing as they were seen walking together in the base. Koarai was enthusiastic about Sasamori's one victory against Hyuse.

Tatsuhito Ikoma
Koarai and Ikoma are presumably on good terms, with Koarai feeling entitled to bemoan Ikoma's involuntary foul when he sparred with Hyuse. Koarai addresses Ikoma by shortening his surname and appending the honorific -san, while Ikoma uses Koarai's nickname and no honorifics.

Kō Murakami
Koarai and Murakami might be close, since the former referred to the latter by his first name, albeit with the addition of the honorific -san.

Shinnosuke Tsuji
Koarai is presumably somewhat close with Tsuji, taunting him when they clashed in round four. For his part, Tsuji appears not to mind Koarai's informality. Nonetheless, Koarai acknowledges Tsuji's superior swordsmanship and addresses him respectfully, using his surname and the honorific -senpai.

Sumiharu Inukai
Inukai knows Koarai well enough to be able to tell that he would generally prefer to hope in a final shot rather than retreat, as well as to call him by his nickname without adding an honorific.

Nozomi Kako
Kako knows Koarai well enough to be able to accurately guess that it was his idea to give the map for round four a snow setting. She refers to him by his surname followed by the suffix -kun.

Jun Arashiyama
Arashiyama knows Koarai well enough to be able to tell that he would generally prefer to hope in a final shot rather than retreat.

Yūta Miura
Koarai and Miura are familiar with each other at least by sight, although Miura's popularity among younger Attackers could imply that they are closer than that. Koarai addresses him by his surname followed by the honorific -senpai, suggesting respect.

Hyuse
Koarai was deeply impressed with Hyuse's combat prowess. Though losing all five rounds to him and subsequently rooting for his opponents, he later enthusiastically greeted and complimented the recruit, going so far as to invite him to join Azuma Unit.