My Hero Academia's Paranormal Liberation War arc is getting to its first major climax, and the tide has turned pretty quickly. The pro heroes successfully infiltrated the League of Villains' new army and used that intel to launch a bold preemptive surprise attack. However, even though the heroes nearly succeed and taking out the lab of All For One's partner Dr. Ujiko, the mad scientist still manages to unleash his new intelligent Nomu beasts, as well as a power-boosted "Plus Ultra Shigaraki." And in one key foreshadow moment, we also learn that Shigaraki also has a secret weapon that could help him win the war!
My Hero Academia manga chapter 273 sees Shigaraki recovering from his near-death experience, and the massive disintegration wave he unleashed upon his awakening. Shigaraki isn't happy with the state of the war - and especially disappointed with the fact that most of the quick-canceling bullets he stole from Overhaul got ruined - thanks to one hero's last-minute sacrifice.
...Most of the quirk-canceling bullets are gone, yes - but not all of them.
One key panel of the manga reveals that about half a dozen of Overhaul's quirk-canceling bullets survived the heroes' attack / Shigaraki disintegration wave. That's a pretty ominous (if understated) reveal - especially since Shigaraki is about to get into a major battle, right at the site of the storage unit for quirk-canceling bullets.
Indeed, the latest manga ends with Endeavor flying at Shigaraki for the first main bout of the Paranormal Liberation War. However, even though Endeavor knows that Shigaraki's disintegration powers have been boosted to a freaky degree, the no. 1 Pro Hero doesn't yet know that Shigaraki has the true All For One quirk, which allows him to steal other quirks. If that wasn't enough, the quirk-canceling bullets are a horrific trifecta. Shigaraki can take down Endeavor any number of ways that would permanently end the No. 1 hero's career - if not his life.
It's not just Endeavor who is on the chopping block: the quick canceling bullets have planted targets on the backs of Izuku Midoriya, Bakugo, All Might, and any other major good guy who might decide to face Shigaraki. The quirk-canceling bullets are subplot that My Hero Academia has been slow-burning for quite some time now, but fans always knew that they would play a pivotal role in the story, at some point. And there doesn't seem a much more pivotal moment than the one that's unfolding now.