Every shonen hero needs a mentor or two, and in My Hero Academia, Izuku Midoriya has several -- from All Might and the elderly Gran Torino to his homeroom teacher, Shota Aizawa/Eraser Head. Aizawa is lovable for his grumpy attitude and gruff teaching methods, and he may actually be a tribute to a shonen character who came before him.
In the classic shonen series Bleach, protagonist Ichigo Kurosaki meets a mysterious man in black named Zangetsu. Ichigo can only see Zangetsu inside his own private world of horizontal skyscrapers, and in that realm, Zangetsu reaches out as Ichigo's mentor and ally in the fight against evil. Both Zangetsu and Aizawa's temperaments and appearances are incredibly similar, but how do they compare as mentors?
Zangetsu, Ichigo's Inner Ally
The true nature and origin of Zangetsu is complicated and rife with spoilers, but it can be said that this mysterious spiritual entity was within Ichigo's soul from the very start. During the early days of Bleach, Ichigo used a nameless and generic zanpakuto but once it broke, he underwent some serious training with Kisuke Urahara, and Zangetsu soon made his debut. From there, Ichigo could access his true power, not just an off-brand imitation, leading Zangetsu to introduce himself as Ichigo's zanpakuto spirit. Unlike Rukia, though, Zangetsu wasn't living in Ichigo's closet; he existed only within Ichigo's inner world, and he gruffly dispensed valuable nuggets of information and wisdom -- if Ichigo was ready to listen.
Zangetsu may have been Ichigo's staunch ally but he also made no bones about dire situations. It was up to Ichigo to find the strength and resolve to wield Zangetsu correctly, face his inner Hollow and overcome it. Zangetsu could show Ichigo the way but it left to Ichigo to defeat his own self to achieve new heights of power. In this regard, Zangetsu was a wise but humorless guide to the world of spirits, demanding only the best from Ichigo.
Later, when Ichigo faced defeat at the hands of Kenpachi Zaraki, Zangetsu reached out to him and implored that Ichigo show two things: his indomitable will to win and his total trust and reliance on Zangetsu as a partner. Once Ichigo proved his worth, Zangetsu lent him some serious power. Ichigo turned the battle around, claiming victory over Kenpachi at last.
Shota Aizawa, Izuku's Gruff Teacher
My Hero Academia pays loving tribute to classic shonen titles and American comic book characters alike. As such, Izuku's homeroom teacher, Shota Aizawa, has elements of Batman within him, as well the aforementioned Zangetsu of Bleach fame. For one thing, Aizawa bears a physical resemblance to Zangetsu, with his long, shaggy dark hair, short beard, black clothes and expressive eyes. The two characters have a similar personality, too, coldly demanding the best from their students while offering very few safety nets or pep talks along the way. Shota Aizawa even told his students early on that many of them might fail to graduate from U.A. at all, and that no student is guaranteed an easy ride to graduation -- not even the talented Shoto Todoroki or Momo Yaoyorozu. Aizawa also has a minimal sense of humor and little patience for frivolity (even during summer break).
However, Aizawa is not a heartless taskmaster. He genuinely cares about each of his class 1-A students and he is eager to see them all realize their potential and prove themselves worthy. Never will Aizawa write off a student as a lost cause or abandon them; if the student still has faith in themselves, then Aizawa will have faith in them, too. Aizawa is also quick to rush to his students defense, such as during the U.S.J. attack. Moreover, he will push himself to the limit in this endeavor, just like All Might himself.
Aizawa is also something of a peacemaker, seeking to placate the sensationalist media and maintain the positive, professional image of U.A. when interacting with the public. Angry outbursts or wild accusations are the last things that U.A. needs while the League of Villains is running rampant (and there might be a U.A. traitor complicating matters, too).
How Aizawa Pushes The Grumpy Mentor Archetype To The Next Level
Both of these characters are great examples of the moody, stern teacher who means well trope, but Aizawa has a few advantages over his possible Zangetsu inspiration. For one thing, Aizawa is a person, not a zanpakuto spirit, so he can interact with many more people than just the main character inside an inner world. Aizawa also plays off of these different characters quite well, such as with his absolute opposite, the flamboyantly exciting Present Mic (who was once his classmate). They have an endearing "light and dark" duality to them, and the same is true when Aizawa meets up with Ms. Joke, a charming friend of his who teaches at the Ketsubuta school. Fans have noticed that based on their personalities, Quirks and appearances, they are like Batman and the Joker, another pop culture allusion that deepens their relationship.
Aizawa also cheers up My Hero Academia viewers with his distinct brand of accidental humor, such as sleeping in a yellow sleeping bag in class, or making awkward smiles when he's trying to encourager everyone. Aizawa isn't trying to be funny, but he ends up funny anyway, which is perfect for this character.
But when it gets down to which is the better, grumpy mentor, you only have to look at the endearing superhero aspect Aizawa possesses, in which he selflessly risks his life and pushes himself to the limit to defend his students and other innocent people from harm, like a true symbol of peace. Zangetsu can't match that.