Mirio Togata/Relationships

His father
Mirio has an excellent relationship with his father. When Mirio expressed his desire to become a hero, his father warned him that his family's Quirk made it difficult for them to become Heroes, which is why his father gave up on becoming one. Despite the warning, Mirio did not give up on his desire, and his father supported him at all times, in spite of his former views.

Tamaki Amajiki
While they are not on a first name basis, the two have known each other during their time at U.A. Mirio and Tamaki are childhood friends. They first met each other back in third grade, when Mirio decided to approach a shy Tamaki who had just transferred to the school.

Tamaki noted that Mirio had always been strong. The two refer to one another by their first names and were worried for one another when either one went through dangerous and or emotionally stressful situations.

It's heavily implied that Mirio may have given Tamaki his hero name, Suneater. It is often seen of Tamaki referring to Mirio as the sun, as in his eyes, Mirio shines bright like the sun because of his bright and positive personality. Mirio, on the other hand, says Tamaki shines even brighter than the sun itself, thus overshadowing it.

Tamaki and Mirio hold a deep level of respect for one another. Tamaki idolizes Mirio's outgoing personality and tenacity to keep himself motivated and keep a level head, something Tamaki believes he does not possess. Mirio once stated to Tamaki that the reason he was able to give it his all was because of Tamaki; saying that he admired him because despite his insecurity and anxiety, he never runs away and always tries his best, leading Mirio to think he needs to work harder in order to never lose to him.

Tamaki worries about what Mirio can do since he knows him perfectly and knows that Mirio can act recklessly. Mirio was the one who gave him the courage and self-confidence necessary to become a hero, since Tamaki always praised his friend's effort and skills, undervaluing himself. Mirio is one of the reasons why Tamaki grew up a hero.

When Mirio got shot by Shin Nemoto during his fight against Overhaul with the Quirk-Destroying Drug bullet, Tamaki woke himself up out of unconsciousness and felt something bad happen to Mirio. It is implied that right after that, Tamaki went to search for him, and finally carried Mirio out of the building.

At some point before the operation against the Shie Hassaikai, Fat Gum joked with Tamaki after he mentioned that he had never had a fight or argument with Mirio for as long as he’s known him, which claims the two were never on bad terms.

When bringing up the topic of Eri's Rewind Quirk, Tamaki placed his hand on Mirio and mentioned Mirio's Quirk possibly returning as the latter smiled at his friend.

Nejire Hado
While they are not on a first name basis, the two have known each other during their time at U.A. and both show concern for the other in difficult situations. Since the and nejire have similar energetic personalities this often conflicts with Nejire's talkative attitude, much to her chagrin. However, this similar personality also makes it easier for both of them to talk and socialize with each other, unlike Tamaki's quiet nature.

During his third year at U.A., Nejire told Mirio that his growth is extraordinary and tells him that he is happy that the whole school is recognizing him. After Mirio's fight against Class 1-A, Nejire wants to explain Mirio's Quirk to the students and tells them the name of his Quirk and Nejire got a little angry when Mirio didn't let her continue talking, causing Mirio to apologize to her. Nejire became noticeably concerned for Mirio after Sir Nighteye's reunion, shown when she was actively trying to cheer him up and convince him not to be too hard on himself during his depression over Eri's situation.

When Yosetsu mentioned the beauty pageant, Mirio mentions to Izuku and Eri that Nejire will participate in the pageant and Nejire was glad to see them. Nejire told Mirio that she wanted to win the Miss Con Beauty Pageant at the U.A. School Festival and he supported her and told her with confidently tells her that will win. During her performance in the contest, Mirio looked at her impressed by her performance and Nejire noticed it among the audience and was glad to see it. After Nejire wins the contest, Mirio smiled as a sign of congratulation.

During the Paranormal Liberation War, when Mirio returned on the battlefield with his Permeation Quirk restored, Mirio asked him if he was alright and Nejire was happy and tells him that its because he was there she was able to get back up and fight despite being badly burned.

Izuku Midoriya
Prior to The Big 3's introduction, Mirio went out of his way to talk with Izuku. He is rather friendly to Izuku, who at first found Mirio to be strange. After witnessing Mirio's power and technique, Izuku grew to admire Mirio, even thinking that he already seems to be like a Pro Hero in the way he talks.

In return, Mirio seems to hold him in high regard as he was impressed by the latter's ingenuity and in their mock battle, despite only having just met and Izuku being a first-year. When All Might asked if Izuku was suited to an internship with Nighteye, Mirio said that he had been thinking Nighteye would like Izuku from the very beginning. Mirio is eager to help Izuku succeed, offering lots of tips and bits of advice before introducing him to Nighteye.

It is currently unconfirmed how much Mirio knows about Izuku and One For All. He seemed certain that Izuku would meet Sir Nighteye, All Might's former sidekick, and did not look surprised when the retired No. 1 hero summoned him and Izuku to ask him to intercede for the latter. Mirio also took notice of the scars on Izuku's arms, which were caused by One For All.

Izuku was visibly disturbed when he learned that Mirio's Quirk was destroyed by Overhaul, and expressed anger towards the villain for that.

After Nighteye's death, when Izuku sees how optimistic Mirio is, Izuku goes as far as to propose that Mirio could take Izuku's Quirk, indicating how Izuku believes that Mirio is truly the worthier candidate for One For All, like Nighteye had said. However, Mirio turns it down as he has faith that Eri might master her Quirk to restore his and believes in the words of Nighteye about being a hero.

Izuku is impressed by this and accepts Mirio's determination, and it seems they become closer friends afterward. The two get along and Izuku still looks up to Mirio for maintaining a smile in spite of his situation, which is something All Might also did in the face of adversity.

All Might
Mirio respects and admires All Might greatly, even after the latter lost his powers, claiming he could not help being happy after being called in by him. Some of his most outlandish behaviors are similar to the energy of All Might's public persona.

It is unknown if Mirio is aware that he was the top prospective candidate for the Quirk One for All or of the bond Izuku has with him.

Sir Nighteye
Mirio works under him for his Hero Work-Studies. Sir Nighteye views him as a full-fledged student with immense potential, making him believe that Mirio deserves to inherit One For All. Thanks to the training and experience he gained under Nighteye's tutelage, Mirio was able to master his Quirk, which made him one of the strongest students in the U.A. For this reason, Mirio holds a deep respect and admiration for his mentor.

This feeling is reciprocal. Although at first Sir Nighteye only saw Mirio as the most suitable substitute for All Might, over time he began to appreciate Mirio, becoming his most treasured student.

Nighteye's death was a serious blow to Mirio. During his final moments, Mirio ran into his death bed and begged his mentor not to leave as he still had much to learn from him. Nighteye comforted Mirio by using his Foresight Quirk one final time to tell him he'd be a great hero in the future.

Although at first he could not help but cry for his death, Mirio has decided not to be sad because Sir Nighteye was smiling all the time while talking to him and will respect his teachings by also smiling since he is going to be an outstanding Hero in the future. After his death, Mirio accept his mentor's loss.

Eraser Head
Until the Shie Hassaikai Raid, there was little interaction between the two. Mirio respects him as a teacher, and Shota recognizes Mirio as U.A.'s most powerful student, even considering him to be the top candidate for No. 1 Hero over all of the Pro Heroes.

After the rescue of Eri, the loss of Mirio's Permeation Quirk and the death of Sir Nighteye, Shota comforts a disconsolate Mirio, promising that he will look for a way to help him to recover his Quirk.

When Eri is under Shota's custody, Mirio helps him take care of her and it is common to see them together when Eri walks through the U.A. Shota is hopeful that Eri will learn to control her Rewind and thereby, restore Mirio's Permeation.

Ovehaul
Mirio knew about Overhaul from Sir Nighteye's research and was aware of his connection to the Shie Hassaikai and the danger he posed. Mirio met Overhaul in person when he was patrolling with Izuku and tried to avoid combat by feeling a murderous air from him, while telling Izuku that they should leave and allowing Eri to return with him.

While the heroes were doing investigations, Mirio and Izuku both agree they have to stop Overhaul and save Eri from him.

Mirio faced Overhaul alone and gave up nothing to try to stop him. Mirio was angry with him and quickly attacked him after defeating Deidoro Sakaki and Shin Nemoto, Overhaul dodged his attack and started threatening Mirio while calling Eri a curse, making Mirio even more angry.

Mirio dodged Overhaul's attacks during their fight and left him unable to defend himself, declaring that he would defeat him and never hurt Eri again. Overhaul is enraged when Mirio says his real name and orders Shin Nemoto to shoot Quirk-Destroying Drug ​at Mirio.

Despite being hit by a Bullet and having lost his Guirk Mirio stood up and hit him screaming that he will always be Lemillion. Even with serious injuries, he did not give up and kept filming against the Villain, until Izuku's arrival. Sir Nighteye even deduced that at some point Mirio came to scare Overhaul.

Eri
Mirio met Eri while he was on patrol with Izuku, although they do not react well. When Mirio finds out about what was happening to Eri, he blames himself greatly and becomes determined to save her. He is the first person to give her hope that she could be free of Overhaul and the Shie Hassaikai.

Mirio defended Eri and sacrificed his powers to do so, he showed no regret in his choice as it allowed him to get her to safety.

Mirio even has faith that her Quirk can possibly restore his lost powers but he is in no rush to regain them and does not want her to feel guilty about his condition.

He later invites her to the U.A. School Festival and holds her in the air for her to see Izuku perform in the play. He was happy to see her smile at the performance.

The two have had a great relationship since then, as it's been stated that he's a really good friend of hers. She looks up to him, and he acts as a brotherly figure to her.

When Eri was able to use her Quirk successfully after training with insects and lizards, Mirio wanted to help her fellow heroes, so he asked if she could restore his Quirk.

He initially apologizes for taking advantage of Eri but due to the kindness he showed her, Eri claimed that she had been training to help him. During the fight against Tomura Shigaraki, Mirio thanked Eri for allowing him to become a hero again.