Phantom: The Animation - S01

Zwei was just an ordinary guy until a chance encounter changed everything. One night, while walking the streets, he saw a brutal assassination unfold. Though he narrowly escaped the sniper-a girl named Ein-he was captured soon after, his memories of his past life wiped clean. His only way out of execution was a grim deal: train as an assassin beside Ein. Now, trapped in a shadowy underworld, he must find a way to break free and take back the life stolen from him.