the nature of decay.
↳ summary. “ the second all five of my fingers touch your neck, your throat would start crumbling, from the skin inward… you’d turn to dust in under a minute. ” uncanny. macabre. undeniably lethal. the following is a non-exhaustive description of the qualities of the decay quirk, tomura shigaraki’s primary style of combat throughout the majority of the story. this post is to be used predominantly as reference, and may be edited as opinions change and new information is discovered; i am still very new to writing tomura, so i might not get everything on the first go. the information will be rooted from a few sources, including the manga, its wiki, and my own personal headcanons. (essentially, this is just an excuse for me to gush about how interesting tomura’s quirk is.)
↳ overview. we know that decay disintegrates by a touch, but it was never explained how. initially, i weighed on whether or not i want decay to be something closer to rot. in theory, it makes sense; the quirk is called decay, and it does pretty much what it’s described to do. i figured that tomura’s ability just sped up the process, from autolysis to skeletonization to even skeletal decay in a matter of seconds. there’s an issue with that, though: rot can only be applied to things with cells (be it animals, plants, et cetera), and therefore it wouldn’t explain how tomura can use decay on, say, a phone or a computer. you can’t just expect a mechanical object to wither into dust, even if you left it alone for hundreds upon hundreds of years, unless you use some damn strong chemicals, and there’s no evidence suggesting that’s the case with tomura. his ability to decay is more natural, completely physical. similar reasonings can be said for objects such as rocks. thus, despite how appealing it sounds to me (that really could have made for some great horror threads), i think we can knock “rot/expedited decay” out of the list of possibilities.
so we’re back to the simple definition of disintegration. we could, of course, just leave it there and call it a day, but i prefer to dive deeper into the ‘how’. for the love of all that is holy, please take note that i am, by a longshot, no physician or chemist. all of the science behind these quirks, therefore, will be left vague enough to perhaps make some sense. that said, if you do specialize in these topics, i am most certainly sat for a lecture. anyway, with that aside, understanding the ‘how’ is a perfect segue towards an equally-as-interesting topic: the origin of the decay quirk itself.
↳ inception. also known as the science behind the decay quirk. to which, apparently, there was quite a bit of that. go figure.
workshopped by kyudai garaki and all for one, decay is a synthetic copy of the overhaul quirk, though stripped completely of the ability to restore a damaged product back to its original form. in short, the quirk is exclusively engineered to obliterate anything it comes in contact with. therefore, to understand decay, you have to have at least a baseline understanding of overhaul… except that overhaul isn’t explained too thoroughly, either. again, this is speculation and headcanon-piling, so for all intents and purposes i’ll be using @overhual’s personal headcanons about kai’s quirk.
overhaul’s disassembling works pretty simply; he has the ability to manipulate the stored energy in an object such that the only way that energy can be properly released is to push out with great force. it’s similar to an explosion, and in that same vein, releases a degree of heat upon the afflicted target. i won’t go too much into it, myself; that’s meta for astro to write up. however, this becomes important to understand the process of decay itself.
or maybe i should say that it’s important to understand disintegration, which happens when the atomic bonds of molecules are broken down. to do this, there has to be an energy transfer, that which would be absorbed in said bonds. when these bonds break down, they become unable to hold shape. doing so en masse would essentially cause the complete failure of a structure, person, or thing. decay works similarly. in short, tomura has the ability to cause the building blocks of anything palpable to crumble, so long as he can physically plant all five fingers down upon it (early on, at least; later, she gains the ability to decay with less than five fingers). small particles or anything else that might be able to slip through her fingers seem to be completely immune to the effects of decay, which makes sense; if she can’t touch something, she can’t activate her quirk.
disintegration. energy transfer. cool. but that’s not the end of this meta just yet. the cool thing about tomura’s character — not to digress too much from the original intent of this meta — is the fact that, similarly to izuku, we get to grow and develop alongside her. she transitions from this dependent, bullheaded individual into what she perceives as her own villain (though that’s shot down the moment we believe it, too). needless to say, decay is a dangerous quirk from the start, but i’d argue that it wasn’t anything flashy for quite some time. it sort of just seemed like your run-of-the-mill-bad-guy ability that horikoshi wrote in… until it wasn’t. leading me to the next section.
↳ psychology. oh, yes. the psychology of the decay quirk. there seems to be quite a bit involved, as revealed during the events of my villain academia. for the sake of length, i won’t go over everything i noticed, but instead the major points that really construct tomura’s ego.
before i go any further, i just want to dispute a pretty big misconception of tomura’s character: namely, that its skin condition is a result of the decay quirk. that’s completely incorrect. instead, tomura seems to have a psychosomatic reaction to stressors in his life, manifested as itchy and irritable skin. this is called a psychogenic itch. nao, tomura’s mother, believed it to be allergies — that seems to be false as well. that’s why we usually see it scratching when it’s irritable, stressed, or feeling other negative emotions. (i’ll eventually make meta about this, but for now, this is just a correction.)
back to the actual effects of decay, though. tomura’s spotlight during my villain academia is pretty much a love letter to this entire section. we see him overcome insurmountable odds and learn that the only limitation he had was his own psyche (and the same goes to toga and twice, as well). interestingly enough, when tenko was just a child, it seemed as though more attributes of her quirk were on display than we see during the beginning of the manga.
i mean, just look at that. the destruction is insane. it spans into something long-distance, which was clearly something tomura lacked in the beginning of the story. additionally, as shown a few panels before:
a chain of decay. we see nao starting to crumble before tenko even has the opportunity to touch her, something that isn’t exhibited again until tomura’s reawakening. take note that the ability to disintegrate is slightly weaker than what we see during the beginning of the manga, too; it seems as though tomura had to develop into full-on disintegration, rather than the partial destruction we see in the above panels. still, the range at which decay is utilized during the quirk’s first manifestation is much greater than that which we see for a good portion of the story. the question, as usual, is why.
i use the term “reawakening” intentionally; tomura’s ability has always been there, but for whatever reason, it was locked away. though it isn’t explicitly confirmed, the signs all point towards tomura blocking the trauma out of his mind. it’s called dissociative amnesia. this is predominantly to protect oneself from the burden of carrying those memories, and is very different than simply forgetting something. make no mistake; tomura always carried those memories. he simply couldn’t access them until he was under a similar stress as he felt during his time with his biological family.
who knows when tomura forgot what happened; all we know is that by the time we’re introduced to her, she doesn’t remember a thing outside of the day all for one took her in. it’s very likely that they just faded in the years she was under all for one’s wing. we also see, initially, that tomura was hesitant to use the decay quirk as a child, perhaps because of those memories being so close to the surface. this is around the time i think tomura’s complete ability started to ‘weaken’ due to mental blocks.
in what seemed as leveling up was simply the overcoming of mental stressors. this ‘liberated’ version of tomura, spat out towards the end of mva, is someone who didn’t exactly level up, but instead remembered the full extent of her ability. range increased. the extent of his destruction did, too. it’s everything tomura could have done from the very beginning physically, at last unleashed for everyone to see.
its effects are larger than that of when he was a child, but the reasoning for that is obvious: he’s grown since then, and his body has become more physically in-tune for his quirk to operate. if you want to take it a step further, you can even argue that now that he’s embracing his past, the psychological barriers held even as a child have been stripped, leaving him completely untethered.
↳ features. at last, what i initially promised before writing this meta: the special features of the decay quirk, including how it even feels to be decayed. take note that while my main-verse tomura’s decay can disintegrate an object almost simultaneously, prior to her reawakening, she was not able to obliterate something as quickly. thus, the effects of decay could be felt before losing consciousness and, almost instantaneously thereafter, life.
for one, i think the feeling depends on where tomura first touches you. something like a limb would be vastly different than your chest, your face, or what have you, simply due to the fact that different parts of your body would fail first. but generally, the initial impact is the same; fissures form deep within the skin a few inches surrounding tomura’s hand, splitting through meat and muscle. the fissures spread quickly, similarly to splintering a piece of wood, eating away at the proteins that bind someone together. although this part happens quickly, the pain is white hot, and may cause involuntary spasming of the afflicted muscle.
then comes the actual disintegration. this happens from the outside in, so while the cracked skin occurs horizontally across the body, the disintegration occurs vertically. the skin begins to grow stiff and hard, sensitive to the touch; during this time, a tugging sensation inward begins, as though someone is pinching and twisting the afflicted area. the stiff skin may hurt during this time, as it doesn’t want to budge from its typical position. the tugging sensation only heightens, though, enough to begin tearing through the skin and raising wounds, breaching the first layer of flesh. the body can be felt failing and, save for quick amputation, there’s nothing one can do, and certainly nothing that can be done to salvage the affected area.
the fissures eventually breach through bone and successfully disembody the afflicted area; depending on where he touches, this could mean immediate death. the disintegration occurs by those deep fissures branching off of each other, spreading like a great vein system to break down everything in contact. nerves are severed, but the brain is ‘tricked’, still alert to a pain in the damaged area. on a scale from one to ten, the general pain of being decayed sits at a seven or an eight: not excruciating or debilitating, but still can be felt intensely. typically, the most pain comes from the necessity of immediate amputation of the decayed area, as you must cut off a bit of healthy tissue in order to assure that everywhere decay touched has been eradicated.
the smell of a decayed body isn’t particularly pleasant, either; they don’t fade into nothingness upon being decayed, after all. scents of decomposition, blood, and heat are unmistakable, sickly-sweet, akin to a wound that has been sitting for too long and festered.
of course, as stated before, this process occurs almost simultaneously to the contact tomura makes post-mva, so someone wouldn’t even have the chance to feel the effects of decay. regardless, it’s not pleasant in the slightest.
↳ conclusion. decay is a very powerful quirk with untapped potential for a good chunk of the story. intrinsically tied with tomura’s psychology, the extent to which she can wreak havoc is only limited by her mind. the ability itself is centric to energy processing, in which energy is transferred to molecules, causing atomic bonds to break and, as such, making the structure they upheld fail completely, as is the basis for disintegration. though it took some time to completely decay an object or person towards the beginning of my hero academia, tomura can now successfully decimate a target almost instantaneously. if you read this far, thank you for hearing my thoughts!
