Jack-4 (introduced in Tekken 5) is an upgrade of Gun Jack, created by G Corporation and the only one in the Jack series that is non-playable. Like P. Jack, this model has a separate personality. Unlike other models in the Jack series, this one is mass-produced to serve as the foot soldiers of the G Corporation. While these never participate in any tournament, they are sent by G Corporation's Nebraska branch to kill Kazuya Mishima after they no longer need him, and the subsequent battle in Hon-Maru almost results in the death of Heihachi Mishima. However Heihachi survived and blasted far away from Hon-Maru, until he recovered from a comatose for days when the fifth tournament was announced. These specific models have a self-destruct device embedded in them, indicated when one of them peels away its face to reveal a countdown. They also appear as enemies in the Scenario Campaign mode in Tekken 6 and a Tekken 5 flashback chapter of Tekken 7.
