My Hero Academia's story focuses on a young Izuku Midoriya who gains the incredible power of "One for All" after a chance encounter with the world's greatest hero, All Might. With that power at the center of its narrative, My Hero Academia stands as one of the most altruistic and community supporting series around, as it is the power to grant its next user the cumulative strength of all of its pass users. However, that thematic through-line will only ever be as strong as its symbol, and One for All certainly has more than a few loose threads.
It's a unique superpower that keeps getting more unique with every chapter, raising more logistic questions than narrative ones as the series tries a little too hard to build Deku up. This list will be running down a few of the quirks that make this Quirk a little nonsensical.
10 Willingly Giving People It
The way that One for All is "inherited" to its next user is a bit of a strange one. The initial user must willingly give the next person a piece of their DNA to which the successor must ingest. People raised their hands to give Goku spirit power, and Naruto could just slap people's backs to give them some Nine-Tailed chakra, yet All Might has to find the NSFW version of transferring power.
The major caveat here is that the previous user must willingly give their powers. However, the show doesn't really explain what that means, leaving the generalization to fill in the gaps rather than explain the psychology of will. A villain can't exactly steal One for All, but could they instead force it out of someone, or does the user need to like them too?
9 Broken Bones
A major plot point for the series is the fact that Izuku must train to be able to handle One for All. His body is just genuinely too weak to handle the power. The instant that he does use this power, parts of his body, particularly his bones, crack and collapse from the tremendous force.
This raises the question: Why doesn't his body break or just hurt all the time? This is the "will" generalization again where the power acts conveniently to how the main character is feeling. Shouldn't the power just be coursing through Izuku's body? If he's too weak to control it, how is he controlling it enough to stop it from constantly breaking his bones?
8 Passing On Other Quirks
The series has recently revealed that One for All not only allows its user access to the cumulative strength of its past users, but it also passes on the Quirks of those users. The big question here being: Why didn't Izuku have those powers in the first place? For that matter, why did All Might show no sign of ever using more than super strength?
Izuku is still barely able to use half of the super strength thing, yet he's ready for another power on top of it. Out of anything established in the series thus far, this little tidbit seems the most like a last-minute addition.
7 Origins
As the origin story goes, as part of some form of pity or a sick joke, the villain, All for One, granted his seemingly quirkless brother the ability to stockpile strength, knowing full well that this basically does nothing for the average person. However, what he failed to realize was the fact that his brother unknowingly had the power to pass on any stockade of powers that he might have to one other person, thus starting the series' collective history.
Quirks as a whole have a bit of a convenient history, yet there are a lot of details here that raise some questions, the most important being: Who did All for One get that stockpile power from and how did he know he had it? Why do these powers exist? As a whole, they sound way to specific to their situation to have arisen from genuine evolution.
6 Seeing Past Users
As an extension of Izuku learning that he is also gaining the quirks of past users, he also came face to figurative face with one of them. Apparently, the Quirk also allows the user to see and even talk to some conscious embodiment of its alum, at least in Deku's case, as All Might has never personally experienced this. It's not exactly known why or even how this works other than just for future exposition.
Does One for All also pass memories or is a piece of the past user's mind or soul also passed along in what may very well be a terrifying hell in the form of being trapped in a teenager's anxious mind?
5 How Much Strength Is Passed Down
The initial idea of One for All is that the user gets the cumulative strength of the past users. However, what is the extent of this? Deku got the power from a wounded All Might. Does this mean he'll get the weakened version of the Quirk or does he get the powers of peak All Might? Also, did any of the old users have super strength?
As the wording dictates, Deku should only have the cumulative strength of eight other adults. Being able to create enough air pressure to disperse clouds probably takes more power than the strength of fewer than 10 people.
4 One for "All"
To be picky for picky's sake, there's also a bit of a strange wording with the title of the Quirk. "All for One" makes sense. The user is able to take other Quirks for the use of one person. The inverse of that idea, One for All, should be the handing of powers to a lot of people, instead of, like, just one person.
The benefit of the power is not so much a dispersal as it is just waiting in line for the next turn. To be fair, the power does grow with every user, but it's just the one user. Not "All." It's false advertising.
3 Deku's Glow
Another inconsistency of the power is in the way it visually manifests for the user. When Deku uses it, he's shrouded in a green, electrical aura a la going Super Saiyan. However, this green glow seemed to be absent whenever All Might used it.
He kind of just has or grows muscles like the Hulk. Shouldn't Deku also be Hulking or Shazaming his way to being a superhero? Also, why isn't All Might surprised by the fact it's different on Izuku? Is this not the first time? Did the author forget to draw the aura on All Might or is he just genuinely a special exception?
2 "Leftover Embers"
As an added benefit of One for All (among its growing list of Kryptonian like benefits), the past users also get to maintain a bit of their powers for some time. The question remains: for how long and how much? It seemed that All Might's fight with All for One should've been his last, yet he still has One for All.
The only explanation for this is that this allows All Might to be sidelined while still useful for when a main character needs saving. i.e. "leftover embers" just means potential plot convenience.
1 How Often It Can Be Passed Down At Once
In a world where All for One is seemingly immortal and new, vastly more powerful threats are looming in the horizon, this begs the question, "Why are they not mainlining this?" That is to say, why can't a bunch of people (at the very least, trustworthy and reliable) get in a room and just constantly pass on the power to keep building its power?
For that matter, could two people also just do this? All Might doesn't seem too worried about losing all his strength as a person, meaning that One for All copies and adds power rather than takes it from the previous users, meaning there could be an exponential effect to two people just consistently trading it off. Until the series goes more in depth into how it works, this is totally a possible scenario.