Chapter : MCs system explained
So to understand MCs actual quirk, he has the abilities of Henry stickman(choices and references)
So his quirk is actually a system that allows him to summon or use certain references from media.
Like if he wanted to stop himeko toga from stabbing him, he would have time stop as options are shown and he has to choose the right one like in the game Henry stickman.
If he fails using his chosen option he retries until he gets the right one.
Now the system isn't exactly a quirk so to say, but if he fulfills certain conditions the mc will be given a permanent buff or item like blood regeneration or the crucible blade from doom eternal.
Example: he wakes up to find two different quest like choices that he has to do,like choose the right options on the first try for a certain number of times in a day or do a certain action and in exchange he gets a reward based on which option he chose.
Example: choose a right option five times for a super jump ability or put laxatives in aizawa's coffe for a gene seed
So if he completes the daily option of his choose he gets said reward.
So basically he's a hero with the powers of Henry stickman.
Hope that made sens to you all.