Tomura Shigaraki/Relationships

All For One
All For One is Tomura's teacher and the one who saved Tomura in his childhood as well as grooming Tomura to be his successor. Ever since then, Tomura looked up to All For One. All For One is very committed to his role as Tomura's teacher and giving him the opportunity to grow and think for himself. All For One was happy to see Tomura think and lead for himself after his Vanguard Action Squad captured Katsuki Bakugo and decided to stop the Pro Heroes and Police Force from apprehending him. Through numerous parallels, it become clear that Tomura's relationship with All For One is similar to Izuku Midoriya's relationship with All Might, as they show concern for each others safety.

It is unknown if he is aware or cares that All For One was the one who killed his grandmother, Nana Shimura.

Kurogiri
Kurogiri is loyal towards Tomura, doing whatever he orders. Tomura appears to value Kurogiri, considering him to be important during the League of Villains's attack on the USJ. While Kurogiri generally follows Tomura's orders, he will also act against his will if he believes that Tomura is acting too hotheadedly such as stopping him from attacking people he considers valuable.

Kurogiri also occasionally talks over Tomura for the same reason, acting like somewhat of a mentor. He appears to understand Tomura's inner thoughts and behaviors, and therefore attempts to act with Tomura's best interest in mind. He may have been put in charge of Tomura by All For One to help oversee his growth.

Tomura is slightly annoyed after Kurogiri's capture as it meant that is was hard to contact the Doctor, and it is implied by Himiko Toga that Tomura is lonely without him.

Dabi
Upon their first encounter, Dabi was rather disgusted at the sight of Tomura, in which the latter voiced his opinion on how poorly-mannered the newcomer acted, in contrast to Himiko Toga. Furthermore, Dabi refused to answer Tomura's question about his full name, even mentioning his will to spread Stain’s ideology.

This pushed Tomura to kill him, though he was prepared to retaliate as Kurogiri stopped this conflict.

Afterward, Dabi started to follow Tomura's command, despite the fact the two have shown a rather disconnected relationship towards each other. He has also shown to have some faith in Dabi's ability to lead out the Vanguard Action Squad during the Forest Training Camp Arc. Eventually, the two became close comrades after All For One's defeat.

Himiko Toga
At their first encounter, Himiko was excited to see him while he was put off by her nature even vocally questioning her sanity though he appreciated her introducing herself in contrast to Dabi.

However, he tried to kill her after she voiced her admiration for Stain and she was prepared for it but Kurogiri stopped this conflict.

Despite this, he grew to like her overtime and they both share a mutual respect for each other. Tomura expressed great value and care for her as seen when he revealed his face to her and smiled genuinely stating she was an important member and ally.

All Might
Until he attacked the U.A. High School, Tomura never met All Might in person. Despite this, since the very beginning he professes an irrational hatred to All Might.

Tomura hates the society of current Heroes society, considering it all the wrong and erroneous, and focuses all that contempt on All Might, which he considers responsible for this situation. He despises his mere existence, which is what causes regular civilians to be happy about almost everything, perpetuating the status quo.

Apparently, the catalyst of this hatred was an accident in his childhood in which someone close to him died, and no hero came to save him, being rescued only by All for One, who would take him as a disciple and start educating him with his ideals, feeding the flames of that hatred.

They finally met in Unforeseen Simulation Joint Arc, when Tomura ordered a raid in the hopes to kill the symbol of peace. Disappointed because he is not there, Tomura decides to kill the students to see if that makes him appear. With the arrival of All Might, Tomura resumes his murder plan and after a long and arduous battle in which he takes All-might to the ropes, he fails, being forced to retreat after being seriously wounded.

The hatred towards All Might grew even more after he defeated and imprisoned his mentor.

On the other hand, All Might also despised Tomura Shigaraki at first, considering him as a criminal with a crazy desire to cause harm, however, after discovering that he is the grandson of his beloved mentor Nana, his perception about him changes, because now it is impossible to All Might see him as a mere criminal.

Izuku Midoriya
Izuku and Tomura mutually despise each other; Tomura despises Izuku for his admiration of All Might (someone he hates) while Izuku doesn't agree with Tomura's villainous actions. During USJ, Izuku saved All Might, which caused Tomura to take an interest in Izuku as shown when he watched Izuku's match during the U.A. Sports Festival. Later in Kiyashi Ward Shopping Mall (Wookiees), they unintentionally met each other again, so Tomura decided to talk with Izuku about the difference between him and Stain. Tomura also made sure Izuku didn't try to struggle by threatening him and the civilians in the area.

After hearing Izuku's thoughts on the matter, Tomura realized his goal and thanked Izuku for helping him see it was clear that All Might needs to be eliminated. Before leaving the shopping mall, Tomura declared that the next time they met, he would show Izuku no mercy.

Tomura is considered a dark reflection of Izuku. While Izuku is working to become the greatest hero, Tomura is working to become the greatest villain.

Katsuki Bakugo
Tomura first met him in the USJ, he nearly attacked Katsuki and the others before All Might appeared. It is shown he took an interest in him after the latter won the U.A. Sports Festival and made plans to procure him, which was successful.

When they met again, Tomura offered him a place in his organization since they both want to do what they want. Katsuki refused as he voiced his admiration to All Might and was intent on being a hero. Katsuki even attacked Tomura and stood defiant at the latter's possible retaliation. At the end, Katsuki was rescued by his classmates and likely considers Tomura an enemy.

Stain
Tomura has a deep disdain for Hero Killer: Stain. They first met when Kurogiri tried to recruit Stain to their party. The meeting went poorly and Stain ended up injuring Tomura, but allowed him to live so that he could gain some conviction and seeing they weren't so different.

This only annoyed Tomura, and he even tried to eliminate the Hero Killer by having the Nomu's ravage Hosu City. This plan ended up backfiring and Stain became more infamous than Tomura and the Nomu's. Even after Stain was captured, his influence continued to bother Tomura. His sympathizers Dabi and Himiko aggravated Tomura to the point where he even decided to attack them.

In order to get this weight off his shoulders, Tomura confronted Izuku Midoriya. After this conversation, Tomura discovers his true hate for Stain comes from his connection with All Might. Wishing to create a world without All Might, Tomura develops his own conviction and states he will use Stain's ideology as a stepping stone for himself.

Overhaul
Tomura showed an intense dislike for Overhaul due to his arrogant attitude after he remarked about their lack of planning. He only sees their influence as a means for his motives. The League of Villains initially had interest in Overhaul and his organization before coming into a disagreement when Overhaul brought up his motives.

The meeting caused a conflict between the two, resulting in casualties on both sides, further angering the league. Despite this unstable relationship on both sides, Overhaul still saw value in the league and encourages them to figure things out before contacting him again.

Overhaul also treats the league with some level of level-headedness and sentiment, as he wanted to bring out the full potential of the league by having them work under him. He only acted violently when the league threw the first punch and apologized to Mr. Compress for destroying his arm.

However, when he was defeated by Izuku and being transported to a hospital Tomura attacked the police escorting him. Tomura voices his reasons for hating Overhaul who was not fazed by their appearance but he got angry when they stole his Quirk drug however, his rage turned to fear as Tomura decayed and cut off one of his arms and Mr. Compress took the other arm. Tomura then gleefully taunted the now helpless and powerless Overhaul who was reduced to screaming as Tomura made off with his creation.