Due to his good looks and kind personality, he is extremely popular among both genders, especially the girls, much to envy of some boys. This is confirmed by many admiring girls surrounding and cheering him, not to mention in some occasions trying to impress him, like Minami Sagami, Yumiko and Iroha. Girls frequently blush in his presence and when they engage in a conversation with him.
As mentioned during Taishi's request, Hayato himself is shown to be aware of his popularity among girls. Most girls have tried to confess to him during the times of rumors which kind of disturbed him.
Hayato's father is a lawyer and his mother is a doctor. So far, they are not officially introduced to the audience. His maternal grandfather is a family doctor to his father. He seems to have a close relationship with his parents. During the summer camp arc, he mentioned that both of them gave him and his clique a lift to Chiba Village summer camp. Yukino has never heard of Hayato going against his family's wishes. His career path choice is affected by his relationship with his parents.
Hayato is known to have a good relationship with the Yukinoshita family. His father is the legal adviser for Mr Yukinoshita. Their families are mentioned to have a feast together during New Year and Christmas. According to Yukino, her mother wishes to have a long lasting relationship with Hayama which she believes will affect Hayato's career choice. But there is more than one way to continue the family friendship other than work, which Hachiman concludes as marriage.
Mrs. Yukinoshita was shown to address Hayato by his first name and formally she apologize to him, for making him wait for the feast. She states that she doesn't know any other classmate of Yukino other than Hayato while meeting Yui & Hachiman.
She is Hayato's childhood friend. Haruno and Hayama call each other by their first name. It was mentioned in the light novel that he and Yukino look up to her. Haruno would also watch over them when both of their families are away on business. In anime version of episode 10 of season 2, Hayato stated that they were often forced to tag along on business because of their family relations.
Hayama comes from the same junior school as Yukino (being in the same class every year) and knows a lot about her, however they have never referred each other as "friends". Hayato is friendly towards her but is quite reserved and never talks back to her. No one in high school knows of their acquaintance with the exception for Hachiman and a few others.
There was an incident involving them in the past resulting in their current strained relationship. Yukino's cold and curt demeanor towards him that shows she hasn't been able to forgive him. Yukino showed hostile behavior towards Hayato during the summer camp in reference to their past and Rumi's current scenario. During their middle school years, there were rumors of them being a couple which spread throughout school, the reason or basis for the rumors are yet to be known.
Their relation was greatly affected by the attention from other classmates. This history is again repeated in high school much to Hayato's dismay. Hayato somehow mostly subdued the rumors on his own. When Hachiman tried to question about it, Hayato changed the topic indicating his difficulty to share the past. Yumiko also felt the same aura from Hayato as to avoid the topic which forced her to visit the service club to know their past relationship.
They finally reconcile somewhat at Hayato's victory party for the marathon. Hayama also noticed Yukino's change of personality and that she no longer closely follows her older sisters path. In episode 12 of season 2, Haruno mentions that Yukino once gave valentines chocolate to Hayato, but he added that she gave it to both himself and Haruno. Even though they have known each-other for a long time, they address each other by their last name. In Episode 10 of season 2 (adapted version of Volume 10) Hayato accidentally addressed Yukino by her nickname, Yuki-chan, hinting that he still feels close to her. But tried to play it off .
Hayama deeply cares about his friends and also tries to prevent his clique from breaking down at multiple points in the series. However, for the most part he failed in solving his clique's problems, especially during the moment when Tobe wanted to confess to Ebina. Due to his conflicting feelings on the matter, he reluctantly asked for Hikigaya's help in solving his group's problem.
His clique is mentioned to be most popular and dominating throughout the school, especially in Class 2-F. They often hangout together and chat in free times. His clique contributed to both class play and ending ceremony of the Culture Festival. During the Athletics festival the majority of his clique were in Team White, with the exception of Yuigahama, who was in Team Red.
However, Hachiman suspects that they only appear to be close and if their relationships were deeper they wouldn't get along well. Hayato mentions to Hachiman that that the clique is all he has and wants to maintain the clique's status quo. Although Hachiman directly accused to Hayato that his clique is superficial, Hayato felt otherwise.
Yumiko is the female lead of Hayato's clique and she seems to have a crush on Hayato, which is clear to everyone and Hayato remains neutral to every girl in the school, including Yumiko. It is hinted he is well-aware of her affections but chooses not to approach the matter as he believes she likes him for the same reasons the other girls do.
She typically agrees to Hayato's demands with the exception of the tennis match where Yumiko refused to back down and wanted to win a match against Yukino Yukinoshita.
Yumiko shows jealousy towards every girl who approaches Hayato, which is shown on the double date incident with Kaori Orimoto. She is greatly disturbed by the rumors revolving around Hayato and Yukino. Despite being close in their clique, there are topics which Yumiko cannot ask or Hayato refuses to answer in his own way, examples of which being his plans for Christmas, or his future career path, and others.
She also can't stand anyone badmouthing Hayato which leads to the hostile behavior towards Yukino in the Chiba summer camp and was also against Saki Kawasaki during the Tokyo visit. At summer camp, Hayato coldly asked Yumiko to stop arguing with Yukino in the summer camp which made her speechless for she saw Hayato's other persona.
Both of them mutually call each other by first name but Hachiman Hikigaya accuses Hayato of using Yumiko to avoid other girls in an attempt to provoke him which is still unanswered by Hayato. Hayato's true feelings of Yumiko are unknown, but Yumiko is trying her best in trying to bridge her gap with him while Hayato remains as emotionally distant as always.
Tobe and Hayato seem to be close friends and get along well. Both of them are the members of the Soccer club. Hayato also escorted Tobe to the service club for his plan to confess to Ebina. But indirectly voiced against it which Tobe couldn't comprehend.Being in the same club, they are more close than other boys in their group.
Hayato is on good terms with both of them. He believes they are "great guys" and gave them positive descriptions, although Yukino and Hachiman believe otherwise, which are proven somewhat true on many occasions. During the chain messages incident, both of them and Tobe competed with each other to be with Hayato in the workplace visit, and one of them started the chain messages depicting all three of them as despicable persons in order to eliminate one out.
Nothing much about their interaction is shown on-screen to the audience, but there are hints of Hina requesting Hayato's help in stopping Tobe from confessing.
Hina is one of the few girls not to have a crush on Hayato and see him only as a friend of hers. However, this does not exclude him from fantasies but he doesn't seem to mind mostly because they are in good terms.
Hayato and Yui call each other by first name. They occasionally exchange messages and have each-others phone number. They view each other in a positive light as Hayato went along with Yui's request to help with Taishi's request.
Both Hayato and Yui have similar traits as they are cheerful and kind to everyone but both have mentioned to Hachiman they aren't as nice as others think. Yui is one of the few girls to just be friendly with him as she has feelings for another boy.
Soubu High School
Isshiki is the manager of the soccer club in which Hayama is the captain. Hayama also knows about Isshiki's façade but doesn't seem to be bothered by it. Iroha has feelings for Hayato, in Episode 10 of season 2 (adapted from Volume 9) she even confessed to Hayama in Destinyland.
Hayato rejected her, most likely due to his "neutral" stance on everything. Hayato also mentions to Hachiman that he was happy about her feelings for him, but suspects they were meant for someone else. However, even after the rejection, Hayama and Isshiki remain companions.
Though they do not have much interaction, Hayato and Saika seem to be on friendly terms. Saika and Hayato even participated in the main roles of Hina's yaoi play, though Hachiman was originally supposed to be in Saika's place. It is shown that Hayato didn't really want to participate in it, but did anyway. Saika was shown to not argue or complain about participating. Hayato, Hachiman, and Saika attended the workplace visit as a group.
Hayato also mentions Saika to be popular with girls, at least equal to him.
Hayato is one of the few people who actually tries to befriend Hachiman, but due to Hachiman's personality, is ultimately kept at a distance. He has the habit of calling Hachiman "Hikitani" even though it is shown that he knows his actual surname.
Due to his own mistakes in the past and his inability to make a difference in crucial moments, he begins to feel inferior to Hachiman because of the ability Hachiman has to change the people around him. Hayato shows shades of his true personality, whenever he talks privately with Hachiman because he thinks that Hachiman is the same as him even though Hachiman himself rejects the idea. Hayato once let slip of words that he can understand why "SHE" looks out for him, but Hachiman lost his chance to ask who or what. Hayato was also about to ask about some one with initial "YU" to Hachiman but lost his chance.
Yukino describes Hayato as the antithesis to Hachiman. While Hayato is kind and outgoing which causes people to be around him very often, Hachiman is not and keeps all of his words to himself, causing the opposite effect to happen. Furthermore, their methods are very different while Hayato seeks to maintain the best of both worlds so that both parties may succeed in problems, Hachiman only cares about getting the job done, regardless of the price that he needs to pay. Hayato's methods often fail and Hachiman's succeed.
Hayato also is saddened and disappointed by the methods that Hikigaya uses to solve issues, due to the fact that he repeatedly self-sacrifices himself to actually solve them. He tried pointing this out to Hachiman during the double date and yet, Hachiman refused to change his mind.
Hayato knows about Hachiman's past crush on Kaori, and surmises that neither of them have actually fallen in love in comparison to his own love life. During the Marathon, Hayato finds out that Hachiman is bothered by rumors and laughed hysterically, as he was surprised.
Like most of the females in her school, Minami is interested in Hayato. She tries appealing herself to Hayato however, he sees through her innocent façade though treats his with usual kindness.
It should be noted that Hayato only followed Tobe's recommendation of Sagami for the Culture Festival class rep and did not directly recommend her. Again Hayato recommended her to the Athletic festival planning committee only after witnessing Yukino, Yui and Shiromeguri's futile attempts to get Sagami to take up the role.
Even though Hayato doesn't view Sagami in good light, he doesn't show it at face value and has always acted in good faith towards her. He also stood up to Hachiman for her but he knew and understood the real reasons for it and reprimands him for his methods.
Kaori seems to be interested in Hayato and was introduced to him by Haruno. Kaori sees Hayama as someone who is cool. It was clear that Hayama wasn't interested in her, however went along with their conversation. When the girls tried to make plans for outing, he tried his own way of avoiding but failed. He also joined her for a double date with Hachiman. Hayama was also aware that she was the girl whom Hachiman liked in the past and expressed his surprise to him.
Hayama showed his cold side to Kaori and her friend for belittling Hachiman and told them not to judge a book by its cover as he introduced them to Yui and Yukino. They ended on bad terms and haven't met again. In the light novel Kaori expresses to Hachiman the difficulty, to see Hayama again.
She is a friend of Kaori and was interested in Hayama. There are no details of them exchanging contacts, but she also went on the double date where she tried her best to appeal to him.
By the end of the double date, she seems saddened and off-put by Hayama's colder side after he defends Hachiman.