What is her source?

First of all, I'll explain this so that I don't have to explain myself over and over again later on. She's from MILGRAM, an interactive music project created by DECO*27 and Takuya Yamanaka. The task of the audience is to decide whether or not to forgive each prisoner based on the info that we get from the animated music videos and the voice dramas, and this is done by voting. Pretty simple, though it's hard to get into it at first. There's also interrogation questions, timeline conversations and minigrams (a light-hearted parody manga), and there's a total of three trials/seasons.

Who is she?

Kotoko is the tenth prisoner, a woman who seems cold and stoic at first glance. She has a very guarded attitude, though as the project progresses and she interacts with the other prisoners, it eases up a little. One of the things that make her who she is is her strong sense of justice, and unlike the other prisoners, she doesn't really see MILGRAM as a bad thing, but rather as a chance to pursue that justice. Rational and logical, she decides to observe and analyze her surroundings in the prison. She's confident in her own actions, showing absolutely no regret for what she does in order to execute her justice.

" Last is prisoner number ten, Kotoko Yuzuriha. Be careful of this one. Just from looking at her, I can tell she's no ordinary woman. "

Her first appearance isn't in her first voice drama, but in Mikoto's voice drama, the ninth prisoner. As he attacks the prison guard, Es, Kotoko intervenes, sneaking in the interrogation room and knocking him out without difficulty. She's the first one to point out Mikoto's DID based on her own observations and conclusions.

Later on, during her first voice drama, she proposes to work together with the guard, claiming that she'd cooperate with them if they decide she's forgiven in the first trial. During the first season, she comes to her own conclusions not only about the nature of MILGRAM, but also about the other prisoners and their verdicts. At the end of the season, Kotoko receives a forgiven verdict with 67.41% of the votes, giving her the highest forgiven percentage so far (as she deserves). She takes this as a green-light from the guard.

" If I can be forgiven, then... Let's shake hands. We will become companions. When the time comes, Es, let me be your fangs. "

After the first trial ends and before the second trial starts, she proceeds to carry on with her plans to cooperate with Es: she attempts to attack all of the prisoners who were unforgiven in the first trial. Mahiru and Fuuta, prisoners number six and three, end up receiving major injuries as a result, with Fuuta losing an eye and Mahiru being left on the verge of death. As for Fuuta, another prisoner, Kazui, stops Kotoko before she can injure him further. Mikoto is a victim of Kotoko's attacks as well, but because of his alter being able to put up a fight, he isn't as badly injured. Kotoko spares Amane, the eighth prisoner, from her attacks. Later on she claims that this was because she had no time left anymore.

Es is clearly unhappy with the way she handles things, and during her second voice drama, they claim that they will not longer work with her. This only reinforces Kotoko's views and her belief that she should have been the prison guard instead, since Es is "too weak" and forgiving to handle things in MILGRAM, according to her. During the second season, it's also clear how her relationships with the other prisoners have greatly deteriodated. At the end of the second trial, Kotoko receives an unforgiven verdict with 75.90% of the votes, giving her the highest unforgiven percentage so far. (I absolutely love how she went from the highest forgiven ratio to the highest unforgiven ratio.)

" Violence... you call it? Being angry at me for hurting your precious prisoners... Heh... This isn't even violence at all. "

What is her crime?

In her first music video, Harrow, Kotoko is shown to be a vigilante- someone who tracks down and punishes criminals following her own morals. She makes this a big part of her life, to the point where she sleeps on nothing but a chair and resides in what seems like a warehouse. In Harrow, she punishes several people, and it's unknown how many of them she killed, if any. However, the focus of the MV is set on her only confirmed kill, Tsugumichi Kaneshiro. He has a history of murdering 10 kids, but because of the powerful position of his father, he's able to get away with it. Kotoko catches him when he's kidnapping a little girl (and his next potential victim). She beats him up to death, rescuing the girl. Right after killing Tsugumichi, Kotoko finds herself laughing and smiling, admitting how good it felt.

Later on, in her second trial MV, Deep Cover, it's revealed that Kotoko was already judged by the law in court for her murder. Her case fit the criteria of self-defense under the Japanese law and therefore she was declared innocent. It is believed that the crime she's in MILGRAM for is Tsugumichi's death, but because of this and other little details, there are also theories of Kotoko's victim probably being someone else.

According to a theory that gained popularity after Deep Cover came out, Kotoko could have indirectly killed the little girl she saved. Keiko (the girl's name given by the fandom, since her actual name hasn't been revealed yet) admired Kotoko and followed her around, potentially getting herself involved in Kotoko's vigilantism and killed by one of her targets. While I don't really favor this theory, I felt like it was worth mentioning.

" I never asked for your understanding. My actions, one by one, are bringing the world closer to peace. Useless weaklings should shut up and let me protect them! "

Random facts

She's 20 years old, and her birthday is on December 15th.
She's the tallest female prisoner, 171 cm.
Yuzuriha (杠) means many things, such as lever, pole, carry on the shoulder. Koto (琴) means Japanese harp and Ko (子) means child.
She studies at the faculty of law, but she was on a break from her studies before arriving at MILGRAM. According to her, the reason why she decided to study law was because she had her suspicions and wanted to have proper knowledge.
Besides Japanese, she's also fluent in English and she can speak Korean and Chinese on a basic level.
She learnt taekwondo when she was in elementary school. She also mentions that when she was a kid, she was already the person she's today.
She used to frequent karaoke's, since the rooms allowed her to have conversations without being heard.
Her family consists of her grandmother, her father, her mother and her older brother. Her father is an office worker and her mother is a housewife.
She has a wolf motif (dooming her to being the furry joke of the fandom).
Besides her studies and her vigilantism, she's also taken a part-time job as a journalist. Not sure if it's related or not, but in her birthday art, she's carrying a camera with her.
Her birthday flower is monstera. It has a lot of symbolism, but what stands out to me the most is that it's sometimes used as a protective talisman, which fits Kotoko's theme of protection. The monstera flower is also associated with femininity, contrasting the fact that Kotoko is the least femenine woman from all the female characters.
Her birthday fruit is dragon fruit, associated with protection as well.

Kotoko's entire wardrobe seems to consist of Jacques Roulet clothes. Just kidding, but most of her clothes do have "Jacques Roulet" written on them. Apparently, Jacques Roulet was a man accused of being a werewolf and killing a kid. (She's NOT beating the furry allegations.)
Her vigilantism gained popularity and attention in the internet, both positive and negative.
This is most likely related to the last fact (and take this with a grain of salt, since I haven't read the MILGRAM novels that talk about the past MILGRAMS). Her actions may have indirectly influenced the creation of the Justice Alliance. In the novels, the Justice Alliance was anything but an organization and more like a group of random, unrelated people who "killed evil people" and then uploaded the videos of said killings on the internet. There's more to it, but I won't go into detail because again, I haven't read the novels myself. In the interrogation questions of the second trial, Kotoko not only denies knowing about said alliance, but she also claims that they're probably useless if they need to band together to achieve justice.
It's been implied that she uses masculine clothes/looks in order to confuse the police. From one of the articles in Harrow: "A pair of men's sneakers were found at the scene. Investigators are narrowing down the search to male suspects. A young man wearing a hood was also seen in the area at the same time."

" It's ridiculous, isn't it? Come on, rely on me, go on. "