Sen Kaibara/Relationships

Neito Monoma
Having a fairly mature attitude, Sen seems to be annoyed with Neito’s disdainful attitude towards Class 1-A, as during the Cavalry Battle of the U.A. Sports Festival Arc, he told exasperatedly told Neito to not antagonize Katsuki Bakugo and to simply move along. Like quite a few of his classmates, he does not seem to have a positive opinion of Neito.

Juzo Honenuki
Based on their interactions in the Joint Training Arc, Sen seems to hold great respect for Juzo's intellect and technique, notable by him addressing his classmate by his first name. When Shoto Todoroki attempted to freeze his team during Round 3, Juzo quickly softened the ice that covered his teammates. Sen immediately praises Juzo for saving Class 1-B from losing and remarks that the latter's counter-reflexes are flexible.

Tetsutetsu Tetsutetsu
Sen appears to be straightforward and honest towards Tetsutetsu. Sen often has to remind him of the flaws of plans, as seen during Round 3 of the Joint Training Battle. He also appears to be annoyed when Tetsutetsu disregards the negatives of facing Class 1-A when the latter chooses to initiate a "head-on-head combat" plan. Despite this, Sen gets along with his fellow classmate pretty well.

Kosei Tsuburaba
Kosei and Sen appear to be good friends. The two have teamed up during the U.A. Sports Festival and followed Neito Monoma's plan in an attempt to defeat Class 1-A. Kosei is also one of the few who can make Sen smile at times when he's not in his stoic persona.