In Asia, a mysterious assassin organization operates under the guise of a noodle shop hidden in a bustling city, serving as a haven for killers. Assassin No. 4, orphaned at a young age and raised in the noodle shop, is sent to Japan to eliminate a yakuza boss. However, he is unexpectedly ambushed by his client, a Japanese girl seeking revenge. To exact her vengeance, she spares no expense in hiring the assassin and attempts to enlist No. 4 in her grand revenge plan, only for their actions to inadvertently provoke a relentless pursuit by the yakuza, putting both their lives in danger…