Izuku thinks the worst the idiots in his class can do is call him names and beat up on him. Until Katsuki takes issue with Izuku getting stronger and gets one of the extras that hang around him to use their quirk on Izuku. That quirk connects the person to their universal counterpart. Izuku's is Nagisa Shiota.

A more detailed look into what happened to Izuku during the events of "a different sensei'

Midoriya Izuku disappeared right after he digested All Might's hair, not that anyone knows that. The Midoriya Izuku who attends the UA entrance exam sets off red alarm bells, especially in a certain underground, sleep-deprived Aizawa Shouta.

15 years ago, a villain destroyed 70% of the moon, defeating all heroes with speed. He was killed in a mega-assassination attempt by World Superpowers, but in reality, a group of trained teenage assassins killed him. The government concealed this fact, and now these former assassins live normal lives. The focus is on a quirkless boy aspiring to be a hero who gets trained by them.

The misadventures of Izuku Midoriya and his band of outcast weirdos. From spending the last year of middle school plotting the assassination of their teacher to pranking their classmates during their first year at UA High.

Izuku made it through his third year at Aldera. He graduated, both from his middle school and from the Assassination Classroom. Now, he has new problems to deal with. New classmates, new teachers, and a whole new type of weird that comes with studying at Japan's top hero school while also trying to hide state secrets. (Part 19 of Open Doors)

Izuku, having survived and graduated from Koro-Sensei's assassination classroom is now ready to face down UA. Quirkless Izuku, most of 3-E being at UA.

The Hero School of UA gets a new Teacher (I Own Nothing)

Hero or assassin, the rules are pretty much the same. In which the invisible girl is a little more unhinged than she seems.

Katsuki is in shock. Deku is in UA. As a recommendation student. He hasn't seen him since Deku transferred to Kunugigaoka Junior High after the jump of the roof like he told him to do. Yet he is deadly confident. Katsuki doesn't like that.

How are we supposed to become heroes when the entire world sees us as assassins?” (Sequel to “To Save the World) (Not my story)

Midoriya Izuku just wanted to escape Bakugou's bullying and achieve his dream of attending the prestigious UA. He assumed the cutthroat Kunugigaoka Junior High would prepare him for that. Too bad he was immediately booted to class 3-E for being quirkless. (not my story)

Shiota Nagisa wakes up in a world where 80% of the population are born with a special ability called a "quirk" and after meeting the aspiring hero, Midoriya Izuku, he, along with class 3E and class 1A get caught into a coming disaster that threatens hero society! Can Nagisa and Izuku save both their comrades and their worlds with a certain time lord? [MHA x AC x DW crossover story]

Nagasi is a young boy with no idea of what to do in his life. But after being saved by an Assassin he is inspired to become one. During his high school year, he and his classmates are being trained by a vicious creature name Koro. Now is up to Nagasi and his classmates show that they are respectful people in this world where heroes are worships as savior. (Explanation inside)

La classe de 3ème E à été invitée à participer au tournois de Yuei. Comment fera l'ancienne classe E pour remporter le tornois. Le feront-ils même ? Et si les combats ramenaient des mauvais souvenirs ? Bienvenue au tournois de l'assassinat ! Spoil sur Assassination classroom et sur My hero academia ! Spoil sur la famille Todoroki aussi !

This is what would happen if Nagisa, Karma, and the teachers were thrown into the world of BNHA. Contains BL and cursing. The image is not mine. OP Nagisa.

When a joint class project in U.A that could not go wrong does go wrong ...

Shiota Nagisa wakes up in a world where 80% of the population are born with a special ability called a "quirk" and after meeting the aspiring hero, Midoriya Izuku, he soon discovers he now has one of his own! What's more, there's a powerful assassin who wants to wipe out all heroes! Can Nagisa and Izuku save both their comrades and their worlds? [MHA x AC crossover story]

It had been little over week since the graduation ceremony, when Nagisa wakes up middle of a forest. He tries to get back home, but notices soon he is lost. Really lost. Story is about assassin prodigy trying to get back home while being hunted down by the government and underground heroes alike, while trying to stay right side of justice.

Dans la société actuelle où quatre-vingts pour cent de la population mondiale a des Alters, chaque personne a grandi en connaissant les Héros et les Vilains. Cependant, il y avait une autre occupation qui était souvent négligée : les Assassins. Si Héros et Vilain sont les deux faces d'une même pièce, alors les Assassins sont le bord de cette pièce.

Hey, It's my first fanfic in English and I don't know what write here, so yah... cof cof After Karasuma send karma and Nagisa to a mission, the blunette and the red one are missing out and don't know where they are and how they Go home I hope you like. bye honey

Denki Kaminari is an orphan living with one of his best friends, desiring to be an incredible hero like the hero Shazam in Kyoto. He will soon get his chance after an incident at the Hatsume Weapons Industry. But when one gets power, they also must learn an important lesson. (Will include AssClass characters later in the story)

10 theoretical duels between characters of the two animes. Was a reply to a commenter

During a class exchange between UA Class 1-A and Kunugigaoka High Class 3-E, Deku and Nagisa have a heart-to-heart about whether Nagisa should become an Assassin.

我的英雄学院原女向 CP：轰焦冻&边里茜 Todoroki Shoto & Hotori Akane