My Hero Academia is a superhero anime series where caped heroes keep the streets safe from villainy and crime, and during his heyday, the invincible All Might was on top of the hero world. No one, hero or villain, could ever doubt his incredible strength, courage, and charisma, but even he couldn't keep this up forever. All Might needed an heir, and he soon found one.

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All Might barely survived his fight against his nemesis, All For One, and time was running out. He considered appointing Mirio Togata as his heir, but then he chose Izuku Midoriya instead. Izuku was honored to become All Might's student, but Izuku also learned that succeeding All Might is a titanic challenge, and this path comes with many harsh realities.

10 One For All Requires Serious Physical Training

My Hero Academia izuku trianing

Incredibly, Izuku Midoriya spent an entire year training before he even set foot in U.A. High, and his first training montage was a rough one. Izuku pushed himself to the absolute limit to prepare his body for the unique power of One For All, and he needed incredible strength and mental fortitude to see this through.

Izuku probably entertained the idea of giving up many times, and his body came close to breaking down entirely. In the end, though, Izuku pushed through this hellish year of training and proved himself ready for One For All.

9 One For All Clashes With Other Quirks

My Hero Academia All Might — with One For All

In Izuku's case, this particular harsh reality wasn't actually an issue, but in theory, it would be a serious problem for any other successor, such as Mirio Togata. Recent story developments make it clear that, while anyone can receive One For All upon proving themselves worthy, One For All doesn't play nice with other Quirks.

One For All places serious strain on the body, and if a person wields One For All alongside their natural Quirk factor, the strain is too much for the body to bear. This shortens One For All's wielder's lifespan considerably, and any All Might heir except for Izuku would have to contend with this reality.

8 All Might's Heir Becomes A Target For Villains

Tomura Shigaraki decays rubble in My Hero Academia.

Strictly speaking, any pro hero or hero student will become a target for powerful villains sooner or later, but All Might's successor is a special case. All villains know and fear All Might, and the League of Villains or Meta Liberation Army would gladly go after All Might's heir to cut this legacy short.

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All Might's heir will certainly be a strong and brave person, but they aren't completely on All Might's level, so villains will stand a chance. All Might's successor must keep looking over their shoulder for villain assassins who want to end the symbol of peace's legacy forever.

7 All Might's Successor Must Face All For One Eventually

my hero academia All For One gestures to himself

Not only must All Might's heir face villainous assassins, but the heir must also confront the symbol of evil himself, the ancient villain All For One. This villain actually created One For All by accident several generations ago, and any wielder of One For All inherits the destiny to face All For One in mortal combat.

Being All Might's successor also means being One For All's heir, and that, in turn, means facing a destiny that involves All For One. By now, Izuku is certain that he alone, as All Might's heir, can and must face All For One and finally end this decades-long feud. That's quite the burden.

6 Mastering One For All Is Difficult

Anime My Hero Academia Izuku Fights Gran Torino

Even if a person proves worthy in body and mind to succeed All Might, the harsh realities are just beginning. Not only must that heir train to become physically strong enough for One For All, but they must train hard to use that Quirk correctly. One For All isn't a simple tool to wield for anyone.

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It's true that All Might has experience with One For All's use, but that's actually not saying a whole lot. All Might is an iffy coach at best, and Izuku didn't learn much from him. Izuku was lucky that the elderly Gran Torino was around to help train him because no other hero teacher or coach could have helped.

5 All Might's Heir Might Experience Imposter Syndrome & Self-Doubt

My Hero Academia deku sad

No matter how strong, smart, popular, or successful a person may be, everyone suffers doubts and insecurities at times, especially if they feel like they haven't truly earned what they have. Imposter syndrome can affect even the strongest people, including All Might himself.

Being All Might's heir is a huge burden and a serious honor, but it also throws open the doors to self-doubt, especially in the face of difficult training and knowing how powerful All For One is. Any heir would think "can I really do this?" more than a few times while training to succeed All Might.

4 Other Hero Students May Envy All Might's Heir

Class 1-A In My Hero Academia

All Might's heir can try to keep all this secret, but they might confide in a few friends anyway, or other students might figure out what's going on anyway, since they'd see All Might paying close attention to his heir. This can inspire awe, respect, and, of course, envy and worry.

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Being a U.A. student can be a source of pride, but even these proud students may be stuck with serious envy when they learn that their classmate was personally chosen by the great All Might to succeed him. Katsuki Bakugo is certainly envious, since he idolizes All Might as much as Izuku does.

3 The Successor's Friends Or Family May Be Taken Hostage

Inko wants Deku to quit

Izuku lives with his single mother Inko, and already, Inko has plenty to worry about. She is concerned that her only son is pushing himself too hard, and he may lose his life to powerful villains, if he doesn't fall apart while training. But Inko should also be concerned for herself.

Unlike heroes, villains are perfectly willing to take hostages and threaten people to get leverage over heroes, and that would include high-profile heroes such as All Might's sidekick or heir. Although this scenario hasn't actually played out, it's still conceivable that All For One would track down Inko and take her hostage to get to Izuku.

2 Endeavor May Be An Issue

Pro Hero Endeavor frowns at his competition in My Hero Academia

All Might's greatest rival is the flaming hero Endeavor, and while that feud is primary between them, Endeavor might get All Might's heir involved, too. Endeavor already took the step of entering a Quirk marriage to produce an heir who can surpass All Might, after all. He'll do anything to prove his legacy superior to All Might's.

All Might's heir may get unpleasant glares and comments from Endeavor, and All Might's heir must also contend with Endeavor's son, the talented Shoto Todoroki, who longs to become #1 for his own reasons. All Might's heir has no shortage of rivals.

1 Mastering The Bonus Quirks Can Be Tricky

Deku using Blackwhip

Izuku later realized that One For All is like a miniature All For One, in that it contains several other people's Quirk factors inside it. During the joint training exercise at school, Izuku panicked as the Blackwhip Quirk emerged, a legacy of One For All's fifth wielder. Izuku needed Ochaco and Hitoshi Shinso's help to get it under control.

Discovering and controlling Blackwhip is an ordeal all on its own, and Izuku will have six more Quirk factors to discover and master after this, too. It must be tricky, juggling so many new and diverse Quirks all at once in addition to One For All itself.

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