Fast Fist

Fast Fist (拳) is the Quirk used by Blackbelt.

Description
The user of Fast Fist can move at least their hands extremely quickly, allowing them to hit at least 100 times in less than a second. Using the Quirk, Blackbelt is able to repeatedly hit near someone's pressure point, eventually hitting it and instantly knocking them unconscious; due to the speed of Fast Fist, the attack appears to be a single chop. It moves fast enough that to the naked eye, it seems like a single motion.

Weaknesses
While the exact control and range of Fast Fist is unclear, it appears to be limited to the hands and arms, as Blackbelt rushed to a crime scene at a normal running pace.