Phantom: Requiem for the Phantom

Synopsis

A teenage Japanese boy wakes up to find himself alone in an empty room with no memory of his own identity or past. He surveys the room he is in and discovers he is a Japanese tourist and suddenly realizes the only thing he can remember is that someone was trying to kill him. While he explores the seemingly abandoned building, he is being monitored by an ominous looking man collecting data on him, he is suddenly attacked again by the masked person from his memories and is told to fight with everything he has or die. Meanwhile, someone is remotely watching his actions. Deciding that he wants to live, he fights back and momentarily gains an advantage; as he attempts to make a killing blow, the mask cracks and his attacker is revealed to be a girl. A vision of a playground is shown the girls true self or soul and the boy's own is shown, the fact that the boy is still unaware of who the girl is after the flashback reveals that the person on the swing next to the girl is in actually his trueself or his soul, when the flash ends reality comes back into play. He attempts to leave but finds himself surrounded by a desert and the girl, no longer attacking him and introduced as Ein, she tells him he will now either live on as an assassin named Zwei or be killed. These scenes are interspersed with a flash forward of Zwei and Ein working together as "Phantom" on an assassination mission. Ein, poses as a maid, along with Zwei, manage to eliminate an entire household of armed guards and the head of a mafia boss in Las Vegas, once again proving their absolute power and indispensability to a mysterious organization called Inferno.

(Source: Wikipedia)