Tobe is friendly with everyone, as he makes conversation with anyone including Hachiman regardless of clique. He was mentioned to have good relations with his clubmates.
Clique
Hayato's clique
Tobe belongs to Hayama's clique. He is friends with Ooka, and Yamato, along with Yumiko Miura, Yui Yuigahama and Hina Ebina, with whom he often hangs out. He is with his clique in all their endeavors. Volunteering at the Chiba summer camp, teaming for the Workplace visit, Class play for Culture Festival, Kyoto trip, etc.
However, during the Kyoto trip, most of the members of the clique are against Tobe's confession to Hina in order to save their status quo. Tobe himself is completely unaware as everyone encouraged him and hid their true feelings.
Ooka & Yamato
Tobe with Ooka and Yamato
Hachiman felt that they treated each-other as "friends of a friend". But their relationship improves greatly after the Workplace tours.
The boys are mentioned to be noisy, and dominate the class atmosphere. Tobe is mentioned to be the noisy one in the group. Tobe hangs out more often with the clique than Ooka or Yamato, as they were absent from Chiba Village summer camp and Destinyland. All the three are members of various sports club.
Hayato Hayama
Hayato and Tobe appear closer friends than any of the other members, this is evident by Hachiman's inquiry to Tobe about Hayato's career path. Hayato is shown with Tobe more than the other members of his clique. They are also on the soccer team together. Hayato also suggested the service club for Tobe's plan to confess to Ebina and escorted him. But Hayato indirectly advised Tobe to back down though he didn't understand.
Hina Ebina
She is the girl whom Tobe harbors feelings for. Tobe's feelings for Hina are mentioned during the Chiba Village summer camp. Tobe asks the service club for help with confessing to her. It was later revealed that Hina actually knows of Kakeru's feelings for her, but does not want to engage in a relationship at the current time, due to her lack of confidence and strange personality. She indirectly requested help from Hachiman to stop Tobe's confession, which Hachiman succeeded in.
But even so, Tobe isn't ready to give up on her.
Tobe eating Hina's valentine chocolate
In Episode 12 of season 2, Hina participated in the pre-valentine collaboration event where she made some valentines chocolate and gave some to Tobe. Hachiman feels that they are a little closer then before and hopes for further progress. Where they stand now is currently unknown.
Yui Yuigahama
Yui seems to be friendly with Tobe. Tobe calls Yui by her first name and Yui sometimes calls him by the nickname, "Tobecchi". Yui agrees that Tobe is a noisy person but doesn't seem to be bothered by it. Yui doesn't hesitate to show her anger towards Tobe when he gave a negative comment about Hachiman. However Yui persuaded the service club to help Tobe and set schemes of her own to get Tobe and Hina closer.
Once in summer camp, Tobe mentioned Yui was cute but an air head which irritated Hachiman, as he feels that Tobe isn't that much different to be able to criticize Yui.
Yumiko Miura
Yumiko and Tobe have a normal relationship and are in the same clique. There are hints of Yumiko helping Tobe's love attempts in the past. Yumiko tends to treat him like a minion. Yumiko disliked the idea of Tobe and Ebina dating as it would disrupt her friendships with the both of them.
Acquaintances
Hachiman Hikigaya
Tobe is the first person to mistakenly address him as Hikitani. It becomes an informal nickname among his clique. After the Chiba Village summer camp and Culture Festival incidents, he gained a very negative opinion of Hachiman, and felt that he is a terrible person. After the Culture Festival, he shared his opinion with everyone. He even made fun of Hachiman by referring to him as Somethingtani-kun.
In the Service Club, he refused to state his request in the presence of Hachiman as he felt the latter had "zero reliability". As the series progresses, Tobe starts to understand Hachiman better.
After the Kyoto field trip Tobe talks to Hachiman in a friendlier manner than before, hinting that all his negative opinions of him have vanished. But he still believes Hachiman's surname is Hikitani and even addressed him by that name, much to the latter's annoyance.
Hachiman agrees with Hayama's opinion of Tobe, after knowing him better, but still feels him to be annoying. Hachiman gives a good impression of Tobe to Hina, when she came to thank him for stopping his confession.
Iroha Isshiki
Tobe and Iroha shopping
Tobe is in the football club which Iroha manages. They are on good terms, and Tobe often helps Iroha in various matters like going shopping together for the club, arranging furniture in student council room, assisting in the pre-valentine event and even helped her confess to Hayama. Tobe acts as a good and reliable senpai while Iroha sees him as an errand boy.
Saki Kawasaki
Saki and Tobe sitting next to each other on the to Kyoto.
Briefly on the bullet train to Kyoto, Hina forces Saki to sit right across from her and right next to Saki. Yui later tells Hachiman that Saki was everything but happy to sit next to Tobe, and Tobe himself was very nervous sitting next to Saki, and is scared of her.
Minami Sagami
Minami bossing around Tobe's clique.
Minami is in the second ranked clique in class 2-F. She seems to regard Tobe's clique with envy.
Minami holds up a facade to disguise her arrogance as innocence, and it is implied that Tobe is unable to see through it, as he recommended her to be the female representative for the cultural festival. Minami, however, doesn't appear to view Tobe as much, she is seen bossing around Tobe, Ooka, and Yamato even though they appear to be working hard.
When he heard of the rooftop incident between Hachiman and Sagami, like most of his classmates he was sympathetic towards her and believes that Hachiman was "seriously terrible". He was mentioned to have a conversation with Minami's cliquein Volume 6.5 and even joined in on their gossiping of Hachiman.