Deku, or Izuku Midoriya, is the leading protagonist and hero-in-training in the popular shonen series My Hero Academia. He started the series as a naive boy who only had one goal: to become a hero. One of the more important mentors in his life is Eraser Head, or Shota Aizawa, his homeroom teacher at his school, U.A. High School.
Throughout the series, Eraser Head has been an invaluable source of information for Deku, leading by example and helping to shape his kids into future heroes. Eraser Head has taught Deku a number of things in his journey to becoming a hero, all of which Deku continues to use in his endeavors.
10 Take Everything Seriously
One of the important lessons that Eraser Head taught Deku was to take everything seriously, regardless of how inconsequential it may seem. This is particularly seen during the Quirk evaluation, when Eraser Head threatened to expel the student who ranked the lowest.
As fans know, this ended up being Deku, and he learned a lesson he'll never forget. While he wasn't expelled even though he scored the lowest, he did take away a valuable lesson. Always take everything seriously, whether it's "only" training or a real mission, to guarantee success.
9 Save Others No Matter The Cost
During the USJ incident, Eraser Head showed Deku what it meant to be a hero and put his life on the line to save others. Deku watched and understood that even though Eraser Head was completely outmatched — especially considering his Quirk's isn't suitable to fight large groups.
Eraser Head continued to fight and did everything he could to protect his students. In this way, Deku learned that being a hero means he must be willing to risk his own life, as he was forced to watch his teacher nearly die while trying to protect them.
8 Observe The Whole Playing Field
Eraser Head also taught Deku to make sure he observes the whole playing field when fighting against opponents. He highlighted that there could always be more going on in a situation than what's on the surface. This is especially seen during the Sports Tournament when Uraraka nearly gets the upper hand on Bakugo by floating all the debris.
From Eraser Head's commentary, Deku learned that sometimes there's more going on in a situation than what's initially expected. Being observant of everything happening in a fight is especially important.
7 Don't Be Reckless With Quirks
One of the first lessons Eraser Head taught Deku was not to be reckless when using his Quirk. During the Quirk Test on his first day, Eraser Head scolded Deku and erased his Quirk after he realized Deku was going to risk breaking his arm just to pass the test.
Eraser Head told Deku he needed to be more careful, as breaking an arm in the middle of a battle would put him at a severe disadvantage, and he needed to think his actions through better. After that, Deku realized how to use his Quirk without being reckless or putting himself at a disadvantage. It's a skill fans see Deku continue to use throughout the series.
6 Be Aware Of Destruction While Fighting
After the first training battle between Bakugo and Deku, Deku learned a valuable lesson from their mistakes. During their fight, they created a giant hole in the building they were in, which would have been extremely dangerous had it been a real hero mission.
While Yaoyorozu technically pointed this detail out to them, it was truly drilled home by Eraser Head during their recap of the exercise. Deku continued to show throughout the series an awareness of his power and strength when it came to his surroundings.
5 Reminded Deku He's Only A Student
One of the important, but less flashy, things Deku learned from Eraser Head was more of a simple reminder — that is, keeping Deku in check as being only a student. This became relevant during the Shie Hassaikai raid, where the students were asked to assist their hero mentors in a huge, dangerous operation.
Eraser Head reminded the students several times that they were only students and not full heroes yet, and that their safety was a top priority. He went as far as to threaten to pull them from the mission if certain conditions happened in order to protect them since they were still young compared to their mentors.
4 Have Multiple Ways To Fight
All heroes have to be able to work in a variety of situations, especially when the odds are stacked against them. "No good hero is a one-trick pony," Eraser Head once said to his class, and it's a lesson that Deku absorbed quickly.
Heroes have to be able to use their Quirk in a variety of ways and fight in different styles in order to be successful. In this way, Eraser Head taught Deku that it's important to have multiple ways to fight with Quirks and to strategize efficiently even when the odds are stacked against him.
3 Breaking The Rules Has Consequences
After Bakugo and Deku's late-night fight, Deku definitively learned about facing the consequences of his actions. While he knew he should not be fighting Bakugo that late without any supervision, Deku still did it in order to help his friend let his emotions out. However, they still broke the rules, and therefore had to face the consequences.
Deku was faced with three days of house arrest as punishment for his actions. Even though he was only fighting because he wanted to help Bakugo, he still had to face up to the consequences of breaking the rules and understood the consequences of his actions.
2 Support Those He Believes In
When Bakugo was kidnapped by the League of Villains, Eraser Head showed Deku and all of Japan an important lesson by standing by those who he believed in. He was not afraid to publicly support Bakugo and his belief that Bakugo would not be turned to the villain's side
Eraser Head maintained his opinion even though many others seemed to have believed Bakugo would turn into a villain. In this way, Eraser Head showed Deku it's important to stand by those who you believe in and trust, especially when they are in vulnerable or unfortunate positions.
1 Fight With Full Strength & Effort
Deku learned another valuable lesson from Eraser Head during the USJ attack: always give full strength when fighting villains, especially if someone's life is on the life. During the incident, Eraser Head was clearly outmatched, with too many opponents and one too strong opponent. He ends up with several serious, seemingly life-threatening injuries.
Still, when Shigaraki moves to use his Quirk on Tsuyu, Eraser Head continued to erase his Quirk and refused to blink. In doing so, he went beyond his own limits and put everything on the line to protect Tsuyu, demonstrating that a hero has to be ready to give any mission their all in order to save those around them.