Knight Hunters: Weiß Kreuz

Aya, Yoji, Ken, and Omi are the four young men who comprise Weiss Kruez (WK), an assassin group who eliminates certain menaces to society. Each member has his own trademark fighting style. Aya is adept at fighting with a katana, Yoji has mastered the art of strangulation via strings, Ken is lethal with his metal claws, while Omi specializes in a wide array of projectiles. (myanimelist.net)