The lead character for Phantom ~Requiem for the Phantom and the visual novel game Phantom of Inferno
Zwei's name was given to him by Scythe Master (zwei means 2 in German). Reiji Azuma was a Japanese tourist visiting America before encountering Ein (Eins means 1 in German) during one of her assassinations. Ein attempted to kill him because he witnessed the assassination, but Reiji managed to evade her for several days before finally being found. Due to the fact that Reiji was able to defeat Inferno's 'Phantom' (the best assassin in the world) without any training for seven days, even refusing to eat that he might be caught and killed, Scythe Master ordered Ein to knockout Reiji because he saw that Reiji's natural survival instinct was perfect for an assassin and it was this strong will that fascinated Scythe Master.
The Phantom Arc
The Naming of Zwei
Reiji overpowers Ein
After his memories are wiped, Reiji wakes up in a room, not knowing who he is or where he is. As he begins to make his way through the building, he is 'hunted' by Ein since Scythe Master wants to know the true strength of Reiji's will to survive. Eventually, EIn finds Reiji and the hunt turns into a close quarter knife fight. When his instinct takes over, Reiji manages to overpower Ein and almost kills her; however, he manages to stop himself before he kills her.
Having proved his abilities to Sycthe Master, Zwei becomes Ein's student in the art of assassination. During the training, Scythe Master comes to pick Ein up for a mission. After Scythe Master and Ein leave, Claudia McCunnen shows up to talk with Zwei. She tells him Inferno's objectives and also gives him hope that he will find out who he is. During three months of training, Zwei is able to become as skilled as Ein - skills which took Ein over a year to learn. At this point, Ein deems that Zwei is ready for his first kill, a man named Captain Wallace. He worked for the Navy SEALs and sold weapons to Inferno, but he didn't just sell them to Inferno, he sold them to many other terrorists. Wallace eventually sullied the name of Inferno and put them in danger of being suspected by the FBI after an FBI agent was found dead in Mexico. Zwei and Wallace are placed outside the same derelict building where Zwei was trained by Ein. Wallace is told that Inferno won't kill him if he kills Zwei. Wallace quickly heads off to the armory to arm himself, and Zwei is told he must kill Wallace. Zwei beats Wallace; however, he hesitates to kill him which allows Wallace to gain the upper hand and beat up Zwei. Just as Wallace is about to shoot Zwei, Zwei's instincts take over and he stabs Wallace in the arm with a combat knife and then shoots Wallace in the head.
Zwei's eyes when his instinct kicks in
For their first assignment together, Ein and Zwei are ordered to kill a mafia boss named Don Lucio. During the shootout against Lucio's bodyguards, Zwei's instinctual skills kick in allowing him to quickly run to Ein whilst avoiding bullets and push her out of the path of 3 more bullets heading for her. It is at this point, Ein remarks later, that she was became scared of Zwei because he had the same eyes as her when he was killing people and dodging bullets.
After wiping out the Tony Stone Mafia based in the west coast of the USA so that Inferno can expand their influence, Ein leaves Zwei in their safe house while she goes to meet Scythe Master. While Ein is gone, Zwei decides to practice driving. Before he leaves, Claudia arrives in her sports car and offers to let Zwei use it to practice driving - whilst making a move on him. Later on, Zwei dreams about himself witnessing the assassination that got him involved with Inferno, up to the point where Ein knocks him out. After waking up, Zwei asks Ein whether she has had any dreams about her past, to which she replies that she has; however, she is apathetic and uninterested in finding out her past. Later on, the two are asked to back up a Phantom operation that consists of stealing 500 kilograms of cocaine. Right as they are about to head out, Zwei is asked to switch jobs and protect Ms. McCunnen in Lizzie's place instead. Though hesitant at first, Ein insists that Zwei follow Ms. McCunnen's orders, so Zwei agrees.
While Zwei is at Claudia's mansion, she gives Zwei his passport and he finds out his real name - Reiji Azuma. After Claudia hands him his passport she tells him that she doesn't need a passive killer like Ein, but someone who wants to do this job, someone who has a strong will. Claudia gives Reiji the option of returning to the life he once had, though she reminds him that it won't be the same now due to his new experiences. Reiji heads to the derelict hideout he started off in to think about his decision.
Bloody knife and bullet after Reiji tends to Ein's wound
When he gets there, he finds Ein lying on the ground wounded after being shot by Lizzie. Reiji gets a call from Claudia informing him that Scythe Master and Ein have betrayed Inferno and that if he helps Ein in any way, Inferno will kill him. Reiji then helps Ein by tending to her wound and getting away from the hideout to avoid being tracked by Inferno.
Reiji - now rejecting the name, Zwei, given to him by Scythe Master, manages to escape with Ein to a hotel; however, when Reiji leaves the hotel, Ein tries to commit suicide, but finds that she can't, due to Reiji's influence on her. Reiji comes back as she is in the act and consoles her. Reiji gives Ein a new name and identity of her own - Elen. Later, while Reiji is attempting to hot wire a car, Elen is captured by Scythe Master and Reiji is captured by Inferno.
Reiji is interrogated and is given a compromise - help Inferno capture/kill Scythe Master and they'll help him get Elen back. Reiji accepts, eager to get revenge on Scythe Master for the things he did to Elen. Inferno manages to track Scythe's whereabouts and begin fighting with Scythe's new allies. They are able to defeat Scythe's reinforcements and, with the help of Reiji, are able to corner Scythe with Lizzie pinning down Elen, who is now working for Scythe again. When Reiji fires a shot at Scythe Master, Elen moves into the path of the bullet takes the shot. Distraught, Reiji falls to his knees. Scythe takes advantage of this and shoots Reiji multiple times before he falls into the sea.
Cal Devens Arc
The story jumps ahead one year. Reiji survived being shot by Scythe and is once again working for Inferno and has taken on his old codename, Zwei. After killing over thirty men in a warehouse as a test, Mr. McGuire appoints Reiji as Phantom, the title reserved for the No.1 assassin in Inferno. When Reiji and Claudia go to meet new clients for Inferno from Japan, they find that the clients have all been killed by a professional assassin. Reiji notices that an innocent bystander was killed by a stray bullet and returns later to give a bouquet of flowers for the killed innocent. Upon returning, Reiji meets a young girl named Cal who tells him that the person who was killed was her sister and that she knows who killed her. Cal says that she'll tell Reiji who it was if he takes her with him, because she wants to see the murderer get killed. Reiji accepts, feeling a closeness with Cal as both of their lives have been destroyed by Inferno's dealings.
To protect Cal from the interrogation by Inferno, Reiji tells them that he'll train Cal to become an assassin since he 'sees something in her'. The excuse is accepted, but Reiji must show proof that Cal has hidden talent. Reiji takes Cal to the complex where he was trained by Ein and, coincidentally, Cal shows a natural affinity for wielding guns, much to Reiji's despair; he didn't want to create another person like himself.
Elen... is alive?
Reiji is asked by Claudia to shadow the Godoh group - the new clients - in case they are attacked again. While at a casino with the Godoh group, he notices that one of their members is missing and finds out that the member went upstairs with a beautiful young girl. Reiji immediately heads up to the room, only to find the member dead. Reiji sees that the murder has only just been committed and quickly rushes to the elevator to catch a glimpse of someone who looks like Elen before the doors close. Later on, Reiji is given the assignment of counter-sniping a meeting being held by Inferno and the Godoh group. Reiji shoots a sniper aiming into the meeting room after finding out who it was; however, another sniper shoots into the meeting room as well.
After Isaac Wisemel is identified by Inferno to be the culprit behind all the murders, Reiji receives a phone call from Lizzie asking him to help her out with the remnants of Wisemel's gang. This turns out to be a trick to lure Reiji out. While Reiji is trying to convince Mr. Godoh that everything is a misunderstanding, they come under attack by a sniper. Reiji pursues the sniper and finds out that it is Elen, who has once again resumed her role as Ein. Before escaping, Ein informs Reiji that Inferno will try to kill him. As he returns to his flat, Reiji sees a bomb explode at his apartment, where he told Cal to wait for him to come back. Reiji kills the Inferno men coming out of the flat before he escapes, believing that Cal is dead. Reiji goes to the derelict hideout and Elen arrives to kill him. After he persuades Elen to not kill him, Elen wishes for him to kill her. Reiji refuses to kill her since he has a promise he needs to keep to her - that he will help her find out who she is. Elen decides to leave Scythe Master and Inferno and escape with Reiji. After getting fake Mexican passports, Reiji and Elen prepare to leave America.
Ein, Zwei and Drei
2 Years on. Reiji and Elen have escaped America and have now settled in Japan, they attempted to live out their lives normally and enrolled in a school. Reiji has a girl named Mio Fujieka whom has a crush on him, Reiji agrees to go on a date with her however during their date a biker does a harmless sneak attack, Reiji immediately recognizes that its one of Inferno's agents. After talking with Elen he finds out that Mio's real last name is actually Godoh, and they can use her as leverage against Inferno because the Godoh group is now part of Inferno. Later on, Reiji meets the biker again and finds out it is Cal, who is still alive and now part of Inferno.
Cal, now named Drei (Drei meaning the number 3 in German), is the new Phantom; however, she feels that to truly become the Phantom she must defeat the previous Phantom - Reiji. Reiji finds out that Scythe picked Cal up and used her hatred for Reiji 'abandoning' her to turn her into a assassin after exposing Claudia to be a traitor and being accepted back into Inferno. After learning form Scythe that Elen is being targeted, Reiji immediately rushes to the church where he knows Elen likes to go and finds Elen and Cal pointing their guns at each other. He attempts to stop the fight but the arrival of Lizzie prevents the fight as she takes Cal away saying to Reiji and Elen that Inferno won't let them off easily. Reiji calls Mr. Shiga - the new boss of the Godoh group - and says that as long as nothing happens to him and Elen, Mio will remain unhurt, allowing Elen to begin making escape plans and while Reiji and Mio continue to date.
Elen and Reiji resume their 'normal lives' once more until Cal takes a personal visit to Mio and Reiji receives threats on his phone from Cal. Reiji tells Elen that he will handle Cal personally but Elen doubts him. Although Elen allows Reiji to think about it, she leaves school early without informing him. She then sends him a message telling him to escape without her, promising to catch up with him once she rescues Mio. Reiji ignores Elen's requests and begins trying to find Elen before she makes her move. He finds Elen in the church waiting for Cal to turn up for an appointed duel between the two. Reiji say's that he'll kill Cal, but Elen still doesn't believe him. Reiji begs Elen to leave so he can deal with Cal, but she tells him she isn't anyone without him - just a person with no memories and no past and so doesn't want him to die.
Eventually Reiji convinces Elen to let him kill Cal. When Cal arrives into the church she tells Reiji why either she has to die or he has to, and begins playing the musical watch Reiji bought her as a child. When it stops playing, they shoot. Reiji proves to be better than Cal and shoots her first. He finally hears Cal's true desire that she just wanted him to love her. He then returns to help Elen fight against the Zahlen Schwestern, who are a group of girls called Vier, Fünf, Sechs, Sieben, Acht, Neun (who are the mass produced versions of Ein, their names mean 4, 5, 6, 7, 8, 9 in German) and Scythe Master.
The Number Sisters
Reiji and Elen lure the Zahlen Schwestern into the school building where they kill two of them before splitting up to fight two each, Reiji kills his two, and Elen kills her two and Scythe Master.
Phantom ~Requiem for the Phantom~
Reiji and Elen both escape and begin their journey to find out who Elen really is, but all they find out is that she is an orphan from Mongolia. This satisfies Elen as she rests under the sky, but in an unexpected turn of events a person going past on a wagon behind Reiji shoots Reiji and we see him fall to the ground, presumably dead (note the fact that he survived getting shot multiple times at close range) and we see Elen lying down looking up at the sky motionless.
Phantom of Inferno
In the original Phantom there are a few differences as to how the story plays out; Reiji's story in the anime follows one path of many to take in the game, which ends in everything major happening as it happened in Requiem. Although Reiji marries Elen in the church before Cal appears and no guy on a wagon comes along and shoots him.