WARNING: The following contains spoilers for My Hero Academia #299, by Kohei Horikoshi, Caleb Cook and John Hunt, available now in English from Viz Media.
Hero society is falling into darkness in the My Hero Academia manga. With dozens of cities reduced to rubble, villains freed from Japan's maximum-security prisons wreaking havoc and many of the best pro-heroes either out of commission or with futures in doubt, Japan faces its darkest hour yet.
In Chapter #299, Hawks and Best Jeanist join forces to investigate how the villains discovered Hawks' true identity, finally revealing the full story behind the dead body Hawks presented to Dabi over 100 chapters ago and resolving one of the manga's most hotly debated mysteries.
The mystery behind the dead body first began after Endeavor defeated the high-end nomu known as Hood. Hawks secretly met up with Dabi in the aftermath and presented him with a shady duffel bag -- which Dabi unzipped to reveal what seemed to be Best Jeanist's corpse. It turns out that Hawks was tasked with killing a major pro-hero to prove his commitment to joining the League of Villains. Either he really had killed Best Jeanist or he'd somehow found a fake good enough to fool everyone.
Whether Best Jeanist was alive or dead remained unknown to readers until the Paranormal Liberation War, where Best Jeanist arrived at a pivotal moment to subdue Gigantomachia. This immediately disproved Dabi's broadcasted assertion that Hawks killed Best Jeanist, which may end up becoming the saving grace that allows the public to doubt the rest of Dabi's claims as well.
Hawks and Best Jeanist reveal the remainder of their trick in Chapter #299 while having a conversation in the latter's car. It seems medical professionals who studied the remains of captured nomu were able to engineer a medical procedure that induces a "deathlike state" in its recipients. Though the toll upon his body was great, Best Jeanist underwent the procedure to convincingly imitate a corpse.
It's a good thing he did -- a cheaper trick or lookalike body wouldn't have worked. Dabi ran tests on Best Jeanist's "corpse" to verify that it really was the #3 pro-hero, and it wouldn't be surprising if Dr. Ujiko had a look at him as well. This involved immense risk on Best Jeanist's part, considering the villains could have cremated or disposed of him at any point, but he was willing to gamble that they would preserve his body for a later nomu experiment.
The gamble paid off. Just before the Paranormal Liberation War, Hawks was able to retrieve Best Jeanist from the warehouse where he was stored. It's unknown if Best Jeanist will suffer any lingering health effects from being in a state of pseudo-death for several months, but considering he was in poor health even before the procedure, he may have seen it as a more valuable contribution to the heroes than anything he could have accomplished on the battlefield in that time.
No matter how clever their plan was in the end, the pro-heroes may be running out of tricks. Endeavor, Hawks and Best Jeanist are up against forces far beyond anything they've yet fought, and more pro-heroes are certainly destined to die before the sun rises once more on a peaceful Japan.