Thirty minutes into “Iron Mask,” the debut feature from Korean writer-director Kim Sung Hwan, its kendo-crazed antihero, Jae-woo (Joo Jong-hyuk), stares trancelike through shadows at an offscreen character, his eyes unblinking. Under fire from his dojo for excessive violence and foul play, Jae-woo’s terse line of self-defense is chilling: “We’re in competition here.”
