Deku's battle against Tomura Shigaraki in the recent chapters of the My Hero Academia manga not only left him completely stripped off of his Quirks, but also without his arms as well. Following the re-emergence of All For One in Shigaraki's body, Deku was left in a completely helpless state in front of the despicable villain.
Fortunately for him, Shota Aizawa and his friends from Class 1-A came to his rescue just in the nick of time, as they not only managed to provide some much-needed backup to Deku, but they also helped him regain his arms with the help of Eri's horn.
As such, a lot of fans were left wondering if Deku would get back his Quirks as well, especially after considering the nature of Eri's Rewind Quirk.
My Hero Academia: Eri's Quirk may be the key to Deku regaining One For All and his other Quirks
In My Hero Academia chapter 420, Shota Aizawa helped Deku regain his arms by piercing him with Eri's horn. In order to save Deku's life, Eri resorted to breaking off her horn with Ectoplasm's help, following which she gave it to Aizawa.
However, since Eri wasn't able to store enough energy for her Rewind Quirk, it took a couple of minutes for Deku's arms to get completely healed.
However, without his Quirks, Deku is just as helpless in front of TomurAFO (Tomura Shigaraki's body with All For One's mind). While his classmates did manage to arrive just in the nick of time to provide some much-needed backup, most of them are almost at their limits at this point of time.
As such, it's doubtful if they will be able to do much damage to TomurAFO in their current state.
Given the current circumstances of the battlefield, Deku certainly needs to get his Quirks back if he wants to put an end to All For One for good. That said, all of his Quirks, including One For All, were transferred to Shigaraki in chapter 417 of the My Hero Academia manga.
Although Shigaraki's consciousness as well as his Decay Quirk had seemingly disappeared following the re-emergence of All For One, it's safe to assume that all of Deku's Quirks are still inside the villain's body.
While it would have normally been impossible for Deku to get his Quirks back from Shigaraki's body, the circumstances have now changed drastically due to Eri's Quirk.
With her Rewind Quirk, Eri can reverse a living being back to its previous state, thereby allowing her to make her target physically younger, heal injuries, and undo bodily modifications.
She is even capable of rewinding a person's body to a point where they get completely erased from existence.
Thereby, it should theoretically be possible for Eri's Quirk to bring back One For All and all the other Quirks in Deku's body, along with his arms. Given that Quirks were initially considered to be mysterious mutations that manifested in humans, the Rewind Quirk should be able to bring back a person's inherent Quirk even if it was taken away.
That said, it should also be taken into account that One For All wasn't Deku's inherent Quirk; it was passed on to him by All Might. As such, it is still impossible to tell if Eri's Rewind would be able to bring back One For All.
Without his Quirks however, Deku currently stands no chance of defeating TomurAFO, irrespective of how many allies he has by his side. As such, it would narratively make sense for him to regain One For All and the rest of his Quirks if he wants to re-enter the battlefield alongside his friends.
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