This Quirk allows the user to build up kinetic energy by repeating regular motions and store it for later use. When the user chooses to release the energy, they gain an explosive burst of speed and power.
The user can choose to only use some of the stored up energy at a time, allowing them to achieve multiple bursts of speed and power.
Deku uses this Quirk while fighting Lady Nagant. He uses Smokescreen to hinder her vision so he can jump around from building to building, gathering kinetic energy before jumping out of a skyscraper and grabbing her.
- Fa Jin is one of the oldest known Quirks in the series along with One For All, All For One, Life Force, Spearlike Bones, and the unnamed luminescence Quirk.
- Fa jin - Wikipedia article about the Chinese martial art technique this Quirk is named after.