Johan's twin sister and the only unharmed survivor of the night when both her parents and her brother were shot in what appeared to be a botched burglary. At first she showed signs of amnesia due to the psychological trauma of the incident. After she and her brother disappeared, she was adopted by the Fortner family from Heidelberg, who were unaware of her previous identity as Anna Liebert. As Nina Fortner, she was a hardworking law student at an unnamed university (likely the University of Heidelberg), as well as an adept practitioner of Aikido. She lived her life in peace until Johan made contact with her on her twentieth birthday. She comes to pursue Johan, albeit by different methods and for a different reason than Tenma.

Dr. Kenzo Tenma is a renowned Japanese brain surgeon working at a leading hospital in Germany. One night, Dr. Tenma risks his reputation and career to save the life of a critically wounded young boy over that of the town mayor who had been planning to support the hospital financially. A string of mysterious murders begin to occur soon after the operation, and Dr. Tenma emerges as the primary suspect despite no incriminating evidence. 
 
A doctor is taught to believe that all life is equal; however, when another series of murders occur in the surgeon's vicinity, Dr. Tenma's beliefs are shaken as his actions that night are shown to have much broader consequences than he could have imagined. Leaving behind his life as a surgeon he embarks on a journey across the country to unravel the mystery of the boy he saved.

[Profile](https://osawa-inc.co.jp/women/notomamiko/)

A Japanese actress, voice actress, and singer. She is married and has one kid.

**Non-anime roles:**
- Shinano - Azur Lane (VG)
- Emma - Goddess of Victory: Nikke (VG)
- Skirk - Genshin Impact (VG)
- Durandal - Honkai Impact 3rd (VG)
- Jun Kazama - Tekken series (VG)
- Mother - Avataro Sentai Donbrothers (Super Sentai) 
- Rella Melancoryphus Cygnus - Metaphor: ReFantazio (VG)
- Yi Xuan - Zenless Zone Zero (VG)

An American stage, television, and voice actress who has provided English language voices for Japanese anime shows, animation, and video games. Some of her major roles are Kallen Stadtfeld in the Code Geass series, Miyuki Takara in Lucky Star, Nina Fortner in Monster, Rider in Studio Deen's Fate/stay night, Suigintou the first Rozen Maiden doll in Rozen Maiden, Sawako Yamanaka in K-On!, Sola-Ui Nuada-Re Sophia-Ri in Fate/Zero, and Momo Hinamori and Soi Fon in Bleach.

In live-action productions, she portrayed Jolene in the television show Weeds.

She is maried to the voice actor [Serge Faliu](https://anilist.co/staff/159217/Serge-Faliu).

Everyone faces uncertainty at some point in their lives. Even a brilliant surgeon like Kenzo Tenma is no exception. But there’s no way he could have known that his decision to stop chasing professional success and instead concentrate on his oath to save peoples’ lives would result in the birth of an abomination. The questions of good and evil now take on a terrifyingly real dimension.
 
Years later, in Germany during the tumultuous post-reunification period, middle-aged childless couples are being killed one after another. The serial killer’s identity is known. The reasons why he kills are not. Dr. Tenma sets out on a journey to find the killer’s twin sister, who may hold some clues to solving the enigma of the “Monster.”
 
(Source: Viz Media)