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……