Looking forward to Marie's reaction lol. Her sister might be cute too. But J will definitely at least be able to make the excuse of 'they hired you to kill me.'
With the tone of this manga, I think there are two realistic situations. Either it happened when J was young and the guy is now totally outclassed, or J let the scar happen because a face scar is hard boiled. lol
Looking forward when J faces the Monster of the Heisei Era. The man who starves for blood and violence. Nothing can stop Nitta. Not even our hard-boiled J.