OVA
Description
Zwei, originally Japanese tourist Reiji Azuma, witnessed an assassination by the elite killer Phantom while visiting Los Angeles. His exceptional survival instincts during the ensuing chase impressed Scythe Master, a leader of Inferno, who spared his life. Reiji underwent memory erasure via drugs and hypnotherapy. Scythe Master then gave him the codename Zwei, signifying his status as the second experimental assassin, and forced him into training under the first Phantom, Ein.

Under Ein, Zwei rapidly mastered firearms, hand-to-hand combat, and knife techniques. His proficiency grew until he defeated Ein in sparring and undertook high-risk missions, assassinating targets such as Navy SEAL Lieutenant Wallace and the family of mafia boss Tony Stone. During these operations, Zwei struggled morally with his actions, though survival remained his prime motivation.

Inferno executive Claudia McCunnen later presented Zwei with his pre-abduction passport, revealing his true identity as Reiji Azuma. This triggered an identity crisis, forcing him to choose between his past life and loyalty to Inferno. When Ein was critically injured on a mission and declared a traitor, Zwei rejected his codename, rescued her, renamed her Eren, and fled with her to Japan seeking normalcy.

In Japan, Reiji and Eren posed as siblings while evading Inferno. Their respite ended when Claudia captured Reiji, offering freedom in exchange for assassinating Scythe Master. Reiji reluctantly embraced the Zwei persona to access his combat skills for the mission. At the confrontation on a San Francisco wharf, Eren took a fatal bullet meant for Scythe Master and fell into the ocean. Scythe Master then shot Reiji, who also sank into the water. Inferno later recovered Reiji and forcibly reinstated him as their new Phantom.

Physically, Reiji has brown hair and eyes. His eyes shift to green with orange centers when his "killing intent" surfaces. His attire changed from casual wear during initial captivity to formal suits as he advanced within Inferno.

Zwei's relationships define key arcs. His bond with Ein/Eren evolved from mentor-student to mutual dependence, culminating in his vow to protect her. He later encountered Cal Devens, a girl seeking vengeance for her murdered sister Judy. Reiji took Cal under his wing, unaware she survived an apartment bombing. She resurfaced as the assassin Drei, harboring deep resentment toward him for abandoning her. Claudia manipulated Zwei for her ambitions. His assigned partner, Lizzie Garland, developed loyalty to him that persisted even after his defection.