Impenetrable Skin (皮膚突き通せない, Hifu tsukitōsenai) is a NEXT ability that, when active, grants the user invulnerability from harm.
The user can become a battering ram capable of plowing through anything or an impassable wall capable of deflecting/halting damage. The user's body becomes able to withstand a significant beating, as a high school-age Rock Bison illustrated to Kotetsu by having his gang members strike him repeatedly with lead pipes which left him unharmed.