My Hero Academia ended its third season by teasing some major players for the fourth season of the series. This includes the Big Three, the top three students of U.A. High School, and Midoriya and the others learned just how far they have to go to be as strong as them.
This was best demonstrated by the top student of U.A., Mirio Togata, as fans saw his level of strength and experience when compared to the first years.
The Big Three came to Class 1-A to explain their upcoming Hero Internships, but after the explanation falls apart, Mirio decides its best to explain it with a demonstration. He challenges the class to fight him all at once, and they oblige. Although they have had experience fighting pro-heroes, villains, and older hero students, they were all easily defeated by Mirio.
Mirio's quirk is permeation, and is a tricky quirk to balance as using it completely strips all sight, sound, and touch sensations from his body. But he's trained his body and power to the point where now it seems like he's warping around. Aizawa notes that Mirio is not only the top student of the school, he's the closest to becoming the number one hero (even factoring in pro-heroes).
Although he seems like a goofy presence thanks to the way his face is designed, and the fact that activating his quirk leaves him nude, every one of his attacks to put down the Class 1-A students was incredibly precise. Midoriya almost lands a hit on him by successfully predicting where he was going to attack from, but Mirio puts him down with his ultimate move (which blinds Midoriya and knocks him out).
After their battle, Midoriya and the others learn just how much they need to improve and how they will need to steel themselves as they head off into the world. The Hero Internships are different this time, as their Provisional Hero Licenses mean they will be treated like pro-heroes in the real world. So Mirio's strength is a reflection of just what they'll need to do in order to be both the top student in the school, and number one hero in the world.
My Hero Academia was created by Kohei Horikoshi and has been running in Shueisha's Weekly Shonen Jump since July 2014. The story follows Izuku Midoriya, who lives in a world where everyone has super powers, even though he was born without them. Dreaming to become a superhero anyway, he's eventually scouted by the world's best hero All Might and enrolls in a school for professional heroes. The series has been collected into 19 volumes so far, and has been licensed by Viz Media for an English language release since 2015.