Still facing the fallout of the "Internship" arc and the hero's attack on Overhaul and the Eight Precepts of Death, the "Internship" arc is nearing its finale as Midoriya deals with everything he's learned.
After learning Mirio was meant to be the original receiver of All Might's One for All power, and seeing Mirio lose his quirk forever, Midoriya goes to Mirio's hospital room in Chapter 162 of the My Hero Academia manga and Mirio proved why he's the best.
Reeling over the death of Nighteye, and feeling guilty for Mirio's current powerlessness, Midoriya asks Mirio if he'd be willing to take his quirk as a replacement. Mirio utterly denies it, however. The panel in which he happily states "No thanks!" has even become a meme in the progress.
Vowing to smile and still be a big hero someday despite his new disability, Mirio declines Midoriya's offer because he doesn't want anyone else to deal with his current hardship. Not only does this hopefully alleviate Midoriya's guilt after learning that Mirio was the one originally meant to inherit One for All, but sets Mirio as a character who refuses to give up in the face of his newly found hardship.
With Nighteye's final words echoing in his mind, Mirio restates his drive to keep smiling and to keep trying anyway. His words and the way he's drawn in Chapter 162 has resonated emotionally with fans and if he wasn't their favorite character in the series before, he is now.
If you're eagerly awaiting the next season of the series, it recently recently a new poster teasing the season as well as another image teasing the season during its official announcement. If that's not enough, why not lookup Horikoshi's original one-shot Barrage? Then, of course, is the currently running manga series that has just wrapped the arc beyond this, the "Internship" arc.
For those unfamiliar with My Hero Academia, the series 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 but 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 15 volumes so far, and has been licensed by Viz Media for an English language release since 2015.