The confrontation happened on a cliffside overlooking the sea. Seven, having already fought through waves of assassins, was weakened. He refused to fight Red Tooth. In the climactic moment, Seven let his guard down , telling Red Tooth that he still considered him a friend.

However, the situation is far more nuanced than a simple betrayal. The stabbing was the culmination of a complex plot involving mind control, a forbidden secret, and Seven’s own decision to abandon his life as the League’s deadliest assassin. To understand the stabbing, you need to understand who Seven was before he lost his memory.

Seven discovered a terrible secret: The leader of the Shadow Killers was using forbidden mind-control arts (the "Poison Pearl" technique) to enslave powerful fighters, turning them into unthinking puppets for the organization. Horrified by this injustice, Seven decided to betray the League. His goal was to steal the antidote/reset code and free these enslaved assassins.

In a tragic turn, the League used Red Tooth's weakness—his sick, younger sister (a character seen in flashbacks)—as leverage. Red Tooth was given a choice: kill Seven, or watch his sister die.

Red Tooth was not merely a villain. He and Seven shared a brotherly bond. When Seven revealed his plan to defect, Red Tooth was torn. He believed that betraying the League meant certain death for both of them. However, the League's leader, sensing Seven's rebellion, ordered Red Tooth to stop him.

Years before the events of the anime, Seven was known as the number-one killer in Xuanwu, unmatched in skill and cold-blooded efficiency. He wore a distinctive white-and-red uniform and wielded the "Thousand Demon Daggers," a sentient blade of immense power. His closest ally was Red Tooth , a fellow top-tier assassin known for his blood-draining abilities and monstrous transformations.