Theory Time: Boku No Hero Academia Aizawa’s Quirk explained! Part 3

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header by @Ruttika_Shin Twitter

Three will do the trick and so we are going into the third round of our Boku no Hero Academia theory time. This time specifically focussing on someone’s quirk: Aizawa Shouta!

Also known as Eraser head by his fellow pro hero colleagues and the outside world, Aizawa’s quirk is something else seen in the whole universe of Boku no Hero academia since his quirk also was explained a bit closer let’s right dive into the topic of how we can see biology from our world playing a big factor in the world of the quirky ones.

Are you ready?

Let’s start right away with today’s Quirk analysis and theory: Erasure!

Aizawa’s Quirk

art by @nanaboodraws on twitter

Starting with the definition from the anime just like his hero name tells us Aizawa Shouta the teacher of class 1-A has a quirk called Erasure.

In fact Aizawa’s quirk is not really erasing the quirk itself but as he mentioned in season 4 episode 6, Aizawa is able to stop the genes responsible for the other person’s quirk for a short period of time, more specifically as long as he doesn’t blink.

Meaning that even if he is not seeing the person after he had nullified the quirk it depends on the time he blinks for the quirk to reactivate.

While his quirk itself is not an offensive type of quirk it is still tied closely to a mechanism that we will later discuss as we see the theory behind his quirk.

But his quirk no matter how powerful it sounds has it’s weak spots as well, for example when it comes to mutant quirks he cannot simply deactivate them since the quirk is the body itself.

Therefore depending on the quirk Aizawa is not able to stop any quirk, so mutant quirks for example are one of them on the other hand if the quirk is an extension of the body let’s take Ojiro’s tail for example, then Aizawa is able to stop the tail from moving with his Erasure since the so-called Quirk genes are located and lumped together yet again if he blinks that’s the moment where his Erasure wears off and the owner of the Quirk is able to use it as if nothing happened.

And here is the interesting part: he does not directly damage the quirk itself but rather like an on-off button he switches the Quirk off and on.

Does it already click which biological process is involved here?

Yes, indeed we are talking about Epigenetics here, for those of you who may have taken a deeper look about Genetics in biology class may already know about it, especially if you are doing your A-levels and have a focus on biology.

But for those of you who don’t have a clue or rather time made them forget about the classes, let me briefly explain what Epigenetics is and how we can see it work with Aizawa’s quirk.

What is Epigenetics?

Epigenetics first of all are a change of genetics, unlike mutations or other gene changes they do not affect the actual genes but merely a reversible changes that can last for a period of time and turn back again. The process does not change the actual DNA sequence but through different kinds of factors and ways Epigenetics can turn the genes off and on if you want to say it a bit more simplified.

In school we often encountered Lamarck and Darwin’s theory which are both different.

If you still have the giraffes visualized in your head both of them had fundamentally diverse theories.

For Darwin’s Theory that was acknowledged and used later on to research more in the evolutionary field of biology, his theory basically says that genes changing is a passive process that does not happen with the will of the one containing the genes (f.e the giraffes). Moreover the genes that had an advantage in surviving the best (survival of the fittest) would establish themselves in the genpool, with giraffe example it would mean that giraffes with long necks had better survival chance back then and due to the faster reproduction and natural selection they became far more than short neck giraffes who had less chances to survive and therefore become quite rare in the genpool if not going extinct.

On the other hand we have Lamarck’s theory, despite it being denied or rather it was refuted it still is used for the means of epigenetics in one way or another. Lamarck’s theory tells us that genes can actively change if desired meaning that in the giraffe example through the desire of wanting to reach the tree the giraffe’s neck grew and stayed like that (simply said).

That theory of actively changing the genes may have been refuted when it comes to the actual DNA sequence but still holds a truth and idea for the process of epigenetics that come from many environmental factors that change the genes without touching the DNA itself.

Epigenetics involves how the genes are read, which means the genes themselves stay untouched but the way they are either read or not gives the effect of the on-off switch.

There are two ways of how the reading of genes can change, that I want to explain to you today which are the most commonly known. 

Therefore you need to know that genes are being read by so-called proteins, we will leave it at that to not complicate things further but give you just a small insight in the world of biology to understand how Aizawa’s quirk works.

A second thing you need to know that DNA can wrap around proteins called histones.

DNA methylation

The first of the two changes that can occur while reading the DNA is methylation/demethylation.

Like the name tells us, in this process a segment of DNA is methylated, meaning that a H3C group attaches itself to the Cytosine which makes it methylated and blocks the protein that reads the DNA from reading it, casually said it turns the gene off.

That same chemical group can be removed which is the process of demethylation as we can say after it is removed the gene is readable again for the protein and simply said, switched on.

Histone modification

Like mentioned before DNA is being able to wrap itself around proteins called histones, the more tightly the DNA is wrapped around the histones the less readable it is.

If the DNA is wrapped tightly around histones then the protein is not able to pass through and read the DNA again this is the process of turning it off as it is not readable.

The other way around, if the DNA loosens and is not wrapped around the histones it’s readable again, the protein can pass through and read the gene.

Here again chemical groups are involved in which if they are attached or not the DNA wraps or unwraps itself from the histones acting as a switch.

Epigenetics and Quirks

@Ruttika_Shin Twitter

Now that we know what epigenetics is and how it works let’s apply it to the world of Boku no Hero academia and explain Aizawa’s quirk.

Why would it make sense that Aizawa’s quirk uses epigenetics and could possibly evoke the two ways of changing the reading of genes?

First of all we see that Aizawa actively uses his quirk to deactivate other people’s quirks which goes back to the active change of gene reading and Lamarck’s theory.

Secondly, Aizawa mentioned in season 4 that he does not damage the genes themselves but rather turns them off while he doesn’t blink after activating his quirk which is another indicator that he is not interfering with the actual DNA sequence but is using epigenetics as a switch that he can control.

Aizawa also cannot use it against mutant quirks since the bodies cannot simply be turned off but if it’s an extension he can make it stop moving for the short amount of time, meaning that as long as the genes are either lumped together in a section or not located directly with other parts of the body that don’t serve as an extension he can use his quirk on them, meaning he turns them off.

Also in the parts before we talked about how closely tied quirks are to genetics and also in the world of Boku no Hero academia Quirks were explained just like a mutation occurring, if you want more information on that, you can read it here and on the other part of our theory time.

We can now assume that if Aizawa activates his quirks two things could happen:

Either his quirk targets the DNA sequences that are responsible for the other person’s quirk and forces the body to attach chemical groups to cause DNA methylation while his quirk is active. Therefore the protein in charge of reading the genes for the quirk are no longer able to pass through and block the user from wielding his/her quirk presuming it’s a non-mutant type. The moment he blinks the body removes the attached chemical groups and causes demethylation which is the moment where the quirk reactivates again making the process reversible and not causing any damage to the actual DNA.

The other possibility would be very similar but instead of DNA methylation Aizawa’s quirk itself targets the histones and chemical group to wrap the DNA around the histones tightly to block the proteins which should read the genes for the quirk turning it off in the short while he doesn’t blink. It would make sense that the moment he blinks the DNA unwraps around the histones and becomes immediately usable again as Aizawa’s focus is not on the person anymore before he can reactivate his quirk to repeat the process.


art by @nanaboodraws on twitter

Despite Aizawa’s quirk not being an offensive weapon, he actively changes the way of quirk genes working and being read, as he himself uses the principle of epigenetic to his advantage and deactivates or rather switches off the quirk for the amount of time he doesn’t blink.

Offensive or not being able to directly interfere with genes and the processes involving epigenetics in general his quirk is an amazing asset when used in a team as depending on the person he is fighting he can even deactivate functions like extensions of a body.

As he activates his quirk and doesn’t need the person to be in his sight afterwards proves that he is able to control the processes inside of the body if he had a look  before and can keep up either methylation or histone modification which would make sense that he doesn’t need to constantly view the quirk user.

What do you think about the biological part of boku no hero academia?

And are there any other theories you have about Aizawa’s quirk?

Drop it in the comments!

Until then I will erase my existence with some tea,



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