Hello. I do not own My Hero Academia or its characters.
Originally I wanted write something different but I do not know how. So I decided to write this since I have a few theories right now that I want to write down. It is a bit of a continuation of the improvement chapter and a bit of me wondering what the limits of certain quirks are.
Midnight: Midnight should be able to put her gas in containers and be able to use them at a later date. It is more the idea for Mina and gaseous acid. It would give Midnight a bit of more control of the area where it should take effect and she would not need to damage her custom so often.
Eraserhead: An easy way to improve Eraserhead would be by giving him a haircut. Shigaraki was only able to predict Eraserhead´s quirk uses because of his hair. I wonder if the effect of Eraser could go through glass or other transparent substances? If yes then he should get new goggles which can protect his eyes from debris and light (flashbangs and the likes) with sun glasses. It is still hard to see what Eraserhead looks at and is protective. The goggles could be even better with thermal vision and night vision function. But with those function there comes up the question of how technology and Eraser interact with each other. Something which I wondered is if Eraser can be reproduce with technology. Depending on what actually suppresses quirks it should be doable. The most likely thing would be vision aka the red eyes. It would make sense since Eraser can only "erase" quirks which are in the line of sight of the user. If this is correct than what suppresses quirks would be a certain frequency. This is something which can be reproduced. It would however not explain why his hair starts to levitate when he uses his quirk. It could simply be a minor quirk inherited from his parent something like Minas horns or Fumikages bird head. If it is not the eyes then either both the change of eye colure and levitating hair are minor quirks and the actual effect of Eraser something completely different or the hair has more to do with it than expected. The effect of the hair however could not be the reason behind Eraser alone otherwise it should be an area effect. So it would probably a combination of the hair and eyes.
Neito Monoma: How much is needed to copy a quirk? It is said that Neito needs to touch the user of the to be copied quirk but would something which contains DNA but is separated from the body be enough to copy another quirk? In the cavalry battle at sport festival Neito copied Kirishimas quirk by touching the red heads hair so I would say Neito only needs something which contains DNA to copy a quirk. Neito cannot use several copied quirks at the same time but would the same apply if he copied All for One, steal a quirk and then try to use the stolen quirk with a copied quirk? By the subject of All for One would Neito keep the stolen quirk? If no what would happen to the quirk? Would it disappear or return to the original user? What would happen if Neito gave away Copy while he still has time with All for One? Would Neito only copy All for One or All for One and all the quirk which were stolen by it as well?
Kamui Wood: Can he control wood outside of his body and let tree grow faster? Can his wood absorb water? This could make it a little bit more fire resistant.
Goodbye with my best regards.