OVA
Description
Ein possesses no memories of her past. The OVA reveals she once had an unnamed older brother; her village suffered massacre before she was sold into a brothel. Rescued by Scythe Master, she endured nearly three years of experimental brainwashing and intense physical conditioning, emerging as the first Phantom of Inferno – the organization's supreme assassin. She served Inferno for over half a year preceding the main story. Escaping to Japan, she adopted the alias Elen. Traces lead back to Ulan Bator, implying Mongolian heritage, though her precise origins remain undefined.

She features short black hair with side bangs framing her cheekbones, and gray eyes that darken in combat. Her typical attire is a yellow Chinese-style top with red trim, a gray skirt, and red dress shoes. Alternate depictions show her with blue leggings replacing the skirt.

Brainwashing initially rendered Ein cold and apathetic, functioning with emotional detachment. She followed orders unquestioningly, viewing herself solely as Scythe Master's tool. Psychologically incapable of autonomous killing, she required explicit commands or acted only in self-defense. Her bond with Zwei ignited gradual emotional growth, leading to fledgling expressions of care and culminating in defiance of Inferno to protect him. She exhibits fierce loyalty to those she bonds with, sacrificing herself for Scythe Master in one path and declaring readiness to protect Zwei at any cost.

As the inaugural Phantom, Ein commands unmatched assassination expertise. Her skills focus on close-quarters combat, utilizing precise knowledge of human anatomy to deliver lethal efficiency – shattering ribs or stopping hearts with minimal motion. She employs a defensive, analytical style, observing opponents before decisive counters. Though proficient with firearms, her tactical acumen is noted, albeit less emphasized than her physical prowess, evidenced when strategically outmaneuvering Drei.

Her relationship with Scythe Master is defined by absolute, brainwashed loyalty; she obeys without hesitation and dies for him willingly. With Zwei, their dynamic evolves from mentorship to deep emotional attachment. She sees him as her "other half," their bond deepening into mutual love and marriage in certain paths. She perceives Drei as a rival and threat, openly admitting hatred fueled by Zwei's past affection. Toward Claudia McCunnen, Ein displays indifference, assisting her only to ease Zwei's distress.

Official media presents divergent paths for Ein. In one arc, she mentors Zwei, escapes Inferno with him as Elen, is later captured, and dies shielding Scythe Master from Zwei's bullet. Another arc sees her survive, orchestrating events undermining Inferno before reuniting with Zwei and fleeing south. The OVA depicts her initial capture of Zwei after he witnesses her assassination, their joint training, and eventual conflict as opposing agents in Inferno's internal strife, culminating in their battle. During their Japanese respite, Ein and Zwei investigate her origins, finding partial solace in Mongolia despite incomplete answers.