Stress

Stress (ストレス) is the Quirk used by Rikiya Yotsubashi.

Description
Rikiya's Quirk grants him the ability to convert stress and anger into raw power. The higher the degree of stress, the larger and tougher the user can make parts of their body. The sheer power gained from this ability is represented by a black marking that spread to enhanced areas of the body.

Rikiya can freely choose any limb to enhance, or he can increase the mass of his entire body. A lone finger was enough to destroy a Double of Twice and single hulking arm annihilated several League of Villains clones with a single swing.