Soubu High SchoolEdit
Iroha didn't seem to establish an equal relationship due to her bullying peers. Iroha is also shown to be more like loner displaying a decent amount of social ability, as she was seen to eat lunch alone in a lively class.
Student CouncilEditIroha's initial relation with the student council members seems to little awkward. Since Iroha is younger and she pretends to be an air head and not make any action as the student council president, and her initial acceptance of all the ideas proposed from Kaihin Sougou High adds up the awkwardness.
But after Hachiman's persuasion of rejecting the ideas and being rejected by Hayama allowed her to have a good relationship with the student council members as she freely asks the vice president for date spots for her mock date with Hachiman. Their relationship is mentioned to be more friendly than before as their duty as the student progress.Episode 10 of Season 2 (adapted from Volume 9 of light novel) she gathered the courage to confess to him in Destinyland, after being influenced by Hachiman's desire for genuine things, but she was rejected.
Hayama later confiding with Hachiman that he rejected her because her true feelings were for another person rather than him. They are still on good terms despite the rejection. Iroha once interviewed Hayato for the school newspaper in Volume 10. Iroha still tries to impress Hayama. In Episode 12 of Season 2, Iroha gave pre-Valentine chocolate to Hayama.
One of the running gags between the pair is the moments involves Iroha misunderstanding of Hachiman's words as an attempt to hit on her, followed by her rejecting him. This dynamic is later given a callback to show the shift in their relationship. She rejected Hachiman six times (up to season 2).
Notably Hachiman treats her much like he does Komachi, unconsciously treating her in ways that he normally only reserves for his little sister. He also feels a sense of responsibility towards her due to his guilt over pushing her to become the president.
She was deeply moved by his desire to have something genuine and inspired by it. She is always surprised by his concern for her which is shown by her reactions during Hachiman's offer to carry her bags. She always seems to rely on Hachiman from the student council election to the Christmas celebration in collaboration with Kaihin Sougou High. When he refused to help her any further after that, she goes to the trouble of requesting Hiratsuka for Hachiman's help as a student council order. She calls him "senpai".
Due to the similarities of their personalities, Hachiman is especially wary of her and mentally grants her a "third grade Hikigaya certificate" for her ability to understand how his mind works. In Volume 10.5, It is shown that Iroha went on a 'mock date' with Hachiman, there have some hints that she may be interested in Hachiman rather than Hayama now. She later uses the receipts from their date as blackmail material.
In Episode 12 of Season 2, when Kaori asked Hachiman whether she has given him any Valentine chocolates before, she looked up in curiosity. In Volume 11 of the light novel, Iroha gave a bag of cookies to Hachiman and asked him to keep it a secret and then went to give Hayama in competing against Yumiko.
Shizuka watches over Iroha like she does with all other students. Iroha mentions to take advice from Shizuka from time to time. In the light novel, Shizuka tried to stand-up for Iroha against her class teacher for the student council candidacy after realizing that it was a prank by her peers. Shizuka is the teacher in charge of all the events that are headed by Iroha like the Christmas collaboration event, the pre-Valentine event and etc.
Once Hachiman refused to help Iroha with her student council work, Iroha went through the trouble of asking Shizuka for Hachiman's help as a student council order which Shizuka sees as a growth in her, but Hachiman saw it as a sly tactics of Iroha.
Iroha first came to the Service Club with a request of losing the election but not in an embarrassing fashion but later Iroha makes herself at home in the club.
After taking the position of president, she regularly visits the Service Club to ask them for favors or make some other request. Though her initial request has already been fulfilled, Hachiman feels a responsibility towards her since he pushed her to become the president, and so he puts up with her whims.
Later in the series, Iroha spends more time in the club and visits frequently with silly excuses. Iroha usually depends on the Service Club for her errands. She was also in Yukino's birthday celebration. At the beginning Hachiman tried questioning her for her visits but Iroha brushed it off.
She is initially frightened by her cold personality and harsh words, but gradually the two take a liking to one another. At one point she comments that the bickering between Yukino and Hachiman about how to treat her resembled a lecture from her parents. Whether Iroha's interest seemingly shifted from Hayato or knowing the rumors to be false, Iroha doesn't seem to be bothered by the rumor of Hayato and Yukino being a couple.
Later in the novels, her interactions with Hachiman appear to bring about a spark of jealousy from Yukino, and she regularly tries to prevent Hachiman and Iroha from spending time alone. However, Yukino seems to have a soft spot much akin to the one she has for Yuigahama, and pampers Iroha somewhat due to her desire to be a good upperclassman.
She has a good relationship with her, calling each other by their first name, though they are only acquaintances through their mutual connection with Hayama prior to Iroha's request. As Iroha becomes a more frequent guest to the Service Club, the two become noticeably more familiar with one another. Just like Yukino, Yui may become jealous or uneasy of Iroha's closeness to Hachiman.
Their alliance continued enough for Iroha to call for another collaboration.They still maintain their facades with each other. Tamanawa calls Iroha by her first name.
In the light novel, Iroha tried to make her appeal to Haruno and was trying to get in the good graces of an influential person but Haruno was able to see through it but goes along with it. Iroha personally told Hachiman how scary Haruno is which made Yukino unpleased.
Haruno learned about the rumor of Hayama and Yukino though Iroha brushed it off. Haruno also chats along with Iroha in the alumni career discussion center which is not shown much to the audience about their subject of discussion.
In Episode 12 of Season 2, Iroha invited Haruno as an instructor for the pre-Valentine collaboration event at the community centre. It is likely they have exchanged their contacts.