Muscle Expansion

Muscle Expansion 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 and Pump Up.
 * The abilities of this Quirk are never shown in neither the manga nor in the anime, only in My Hero Academia: The Strongest Hero.