Upon rereading a few earlier chapters of My Hero Academia, I noticed an oddity regarding Tomura Shigaraki's Quirk. Later in the story, it is revealed that whatever he touches with all five fingers decays uncontrollably until it's reduced to dust, with Tomura needing to be careful not to use his five fingers when manipulating objects he doesn't want to decay; much like Ochako's Quirk.

However, during the attack on the USJ, when Tomura used his power on professor Aizawa, only his elbow was affected, even though his entire body should have decayed. Is there an in-story explanation I missed for this discrepancy, or had Tomura's power not been cemented at that point?

4 Answers 4


As seen with different quirks as well, the user does not always have full control over it. Something which is also seen very well with Eri's quirk Rewind.

So much rather than assuming it's a discrepancy in the plot, the assumption that Shigaraki has no/clumsy control of his quirk is more likely.

Another factor at play might also be the speed at which the decay works. Through out the manga we have seen that the decay can set in almost instantly, but at occasion also act's slowly. Both of which might also be the case due to him not having proper control of his quirk.


Yes, you missed something.

During Shigaraki's fight with Eraseheader, he figures out that Eraserhead's hair 'is his tell'. Namely when Aizawa is using his Quirk, his hair stands up. Shigaraki actually tells Eraseheader this, after waiting for him to blink and grabbing him.

This is relevant because as the Decay starts to spread on Aizawa's elbow, his hair stands up again. This indicates that he shut of Decay again, and that shutting it off also saves the victim (namely Aizawa himself).

  • This is most likely the correct answer.
    – GamerGypps
    May 22, 2020 at 14:52

It might have to do with the Aizawa's quirk.

Aizawa can stop someone from using their quirks, with this in mind there is two situations :

  1. When Aizawa stops a quirk like Tomura's, it also stop it's ongoing effect, if there is one, in this case it would stop the decaying. While it can't revert the effect of the quirk, it can prevent them from progressing further.
  2. When Aizawa stops a quirk like Tomura's, it only stop it's further uses, and any and all effect already active keep on progressing, in wich case it is probably a discrepancy on the part of the author.

Spoilers from the Manga

Aside from Mutant-type Quirks, it appears that people are able to control their abilities. After all, they are extensions of one's body. In the case of Eri, it is simply because she is young that she is incapable of controlling her quirk. This is the same case with Kirishima, who cut his upper eye when he was younger due to his inability to control his quirk, which had just manifested. It is because of this that Aizawa implies that she would be able to master her quirk with enough practice, to the point where she could possibly undo the effects of All for One.

If Shigaraki is incapable of controlling his quirk, then that is likely because he never made the effort to train it, hence why no other canonical character is incapable of controlling their quirk. This would suit Shigaraki's childish personality, as he would likely enjoy the thought of destroying whatever he touches.

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