Muscle Expansion (?)[1] is the Quirk used by Hard Head.
Description[]
Muscle Expansion allows the user to expand and strengthen their muscles, granting them a significant increase in physical strength.
Trivia[]
- This Quirk functions identically to Muscle Augmentation.
- The abilities of this Quirk are never shown in neither the manga nor in the anime, only in My Hero Academia: The Strongest Hero.