Danger Sense

Rendered as Kiki Kanchi in Japanese, this Emitter Quirk operates at whatever range the situation calls for. It surfaces in Chapter 286 and Episode 123, though it goes unnamed until Chapter 295 and Episode 126. Hikage Shinomori held it first, Izuku Midoriya received it as part of his inheritance, and Tomura Shigaraki eventually took it off him.

The function is a sixth sense. Anything in the vicinity that might do the holder harm registers, giving them the opening to react in time. Izuku describes the alert as a sharp stabbing feeling in his head, drawn on the page as a lightning bolt coming down. The colour marks the owner: yellow for Izuku and Hikage, red once Tomura is the one using it.

What it reads is intent rather than motion. Hostile purpose and negative emotion set it off, and it grades threats by severity instead of treating them all alike. Giulio Gandini drew no reaction at all despite aiming a gun at Izuku, since he never meant to fire. Dark Might, by contrast, sent the Quirk into overdrive on presence alone, flagging him as the worst danger the Gollini Family had to offer. The obvious ancestor is Spider-Man's spider-sense, down to the visual shorthand: wavy lines for one, a lightning bolt for the other.

The alert has a price. Izuku reports that it initially punished his body in proportion to the danger it picked up, though this may be One For All amplifying the signal rather than the Quirk's natural state. The strain eased off him over time, which suggests training can dull it.

Warning is not the same as escape. Anything moving fast enough outruns the reaction window, which is how Lady Nagant's rifle round put Izuku in serious condition despite the Quirk firing exactly as designed.

Absence of malice is the larger hole. No genuine threat means no signal, so people trying to help slip past it entirely, and so does anyone whose hostility is not really hostility. Himiko Toga caught Izuku completely unaware for that reason: she came at him out of what she considered affection. The reverse failure exists too. Because it responds passively to hatred, anger, and anxiety, a crowd steeped in negativity floods the holder with alerts, as the protesters objecting to Izuku's return to U.A. demonstrated.

An opponent who understands the mechanism can weaponise it. Izuku kept Tomura's stolen Danger Sense screaming with Blackchain while a Smokescreen-covered attack came in from elsewhere. Threat grading can also be turned inside out: during the final battle the Quirk was so fixated on Izuku that every other hero read as background noise, until the heroes converged at once and the combined signal left "All For One" unable to work out where the danger actually was.

Hikage Shinomori almost certainly paired it with One For All, though nothing survives about how he fought. His only demonstration comes inside the vestige realm: he slips Daigoro Banjo's Blackwhips without apparent effort.

Izuku Midoriya manifested it by accident during the Paranormal Liberation War, in a rage after Tomura's Rivet Stab injured Katsuki Bakugo, and did not understand what he was feeling. The sensation returned as Gigantomachia worked loose from Best Jeanist's wires, and only after Dabi's Blueflame knocked him briefly out did he connect the pain to All Might's notes on the previous holders. Untrained and newly awakened, the Quirk nearly cost him consciousness, but he kept fighting. Later it became his tracking tool while he hunted the League of Villains, following the twinge toward whatever was wrong. His rematch with Muscular showed the refined version, prior knowledge plus early warning making the dodges land, and he leaned on it again through the close-quarters end of his final fight with Tomura.

Tomura Shigaraki stole it during that fight. He came within a hair of grabbing Izuku's face before losing his fingers to a slash, and that fractional contact was enough to take both the Quirk and Hikage's vestige. He used it to slip every Blackchain thrown at him, until Izuku, far more experienced with its limits, engineered the counter. Once "All For One" occupied his body the Quirk turned hypersensitive to Izuku specifically, drowning out every other hero, and was finally swamped by the whole surviving hero force attacking at once.

Being stolen had one unintended consequence: Danger Sense was the sole One For All Quirk to survive the final clash between Tomura and Izuku, since it was no longer there to be destroyed. It was likewise the final Quirk Tomura ever took successfully while wielding All For One, the second such theft after New Order.