Teen Wolf, Season 3

Nogitsune:
Do you know the ritual of seppuku, Stiles?

Stiles:
No, and I don't want to.

Nogitsune:
When a samurai disembowels himself with his own sword to maintain his honor. But, that's not the cut that kills him. The killing stroke is made by his kaishakunin, who beheads the samurai with his own katana. Scott... Scott is your kaishakunin. I'm going to make your best friend kill you, Stiles. And, you're going to let him, because, just like you, they're all going to die. Everyone touched by an oni's blade. [beat] Unless Scott kills you first.

Stiles:
Why? Why are you doing this?

Nogitsune:
To win the game.