Black Rock Shooter - The Game/Yuu Kotari

Yuu Kotari
...can I call you Yomi too?" Yuu to Yomi.

Yuu Koutari (神足ユウ Koutari Yuu) is a supporting character in the OVA Black★Rock Shooter and the following anime. Her "other self" is Strength. She is voiced by Kana Asumi.

Black★Rock Shooter (OVA)
Yuu has choppy tawny hair and hazel eyes. She is also very short in stature, much more so than Mato or Yomi. She wears the same school uniform as the former and latter.

Black★Rock Shooter (Anime)
Yuu's hair is more combed down, and not as choppy as it was in the OVA. She also now wears an orange hairclip on her left side, and wears a school uniform different from her OVA appearance.

Black★Rock Shooter (OVA)
Yuu is excitable and perky; however, she is shown to have a dark side. She is also very possessive of Mato, and has an awkward time whenever she is hanging out with Yomi.

Black★Rock Shooter (Anime)
Similar to her OVA incarnation, she is excitable and perky; she is also eager to tease Mato often. Unlike her OVA incarnation, however, she is perfectly comfortable with the idea of Mato having other friends, and in fact actively teases Mato about her friendship with "her Tiny Bird".

She is fond of skipping classes in favor of drinking coffee at the consultation room. Mato notes that she is trying to be mature for some reason, and indeed she takes concern over Mato's well-being. Mato also says that when she knew her in kindergarten, she was excessively more hyper, and often did "weird things". However, this personality is of Strength, who was in Yuu's body in the real world.

The real Yuu, who was in Strength's body in the Otherworld, was a stoic and silent person who was constantly hurt by bullying and familial problems, and had a vast amount of knowledge of the "other selves" and the Otherworld. Though it seemed as if the pain didn't affect her, she was actually heavily affected by it, to the point where she switched places with Strength because the pain Strength had to endure in the Otherworld was much simpler, only needing to fight and not worry about anything else.

Black★Rock Shooter (OVA)
Yuu first appears when Mato Kuroi gets injured during basketball practice, and she tends to Mato. She is a first year student who becomes accelerated to second year. She ends up as the main cause of Yomi Takanashi's fall into possession by the Dead Master, as her possessiveness of Mato and the fact it is difficult for the three to be as close as two of them would be which creates jealousy inside Yomi.

When Yomi vanishes, Yuu encourages Mato to cheer up, although she seems more concerned about Mato than Yomi.

After Yomi and Mato reconcile, they invite Yuu to come along with them. However, Yuu feels "left out" somehow and approaches them with a dark expression. It is implied she is the next problem Mato or Black★Rock Shooter will have to face.

Her "other self" is not explicitly shown but is implied to be Strength as the two have the same hairstyle, and Strength is shown to be ominously approaching the fighting Black★Rock Shooter and Dead Master while Yuu's dark feelings are starting to surface.

Black★Rock Shooter (2012)
Yuu and Mato had been friends since kindergarten. Mato states that during then, Yuu had been a rather crazy person, doing all sorts of wild and strange things.

Yuu first appears when she greets Mato and walks with her on the way home. She is introduced as a childhood friend of Mato. During the way home, they discuss the strange person named "little birds playing" (Yomi). Yuu guesses correctly that Mato wants to make friends with her. She is also applying to be the manager of the basketball club, and comments when Arata Kohata overworks Mato.

Sometime later, Mato visits Saya Irino, where she finds Yuu skipping class and drinking coffee with five cubes of sugar, her favorite. Yuu listens to Mato's story about her mysterious dream and agrees that it is strange.

Yuu meets Mato some days later and reminds her to come to the meeting with her. After basketball practice, she notes Mato's friendship with her new "Tiny Bird". She and Mato soon see Arata confessing to a boy in her class, handing over a love letter, but she and Mato run off once Arata catches them.

Yuu accompanies Mato to her training trip, generally taking care of her. Mato at one point wakes up in the middle of the night after having had a dream of the Otherworld. She talks to her about it, saying that it might be part of what Saya had told her and Mato: there is "someone out there taking her pain for her", and the girls in her dream might be those. She muses that it would be rather cool for that to be the case.

While they go souvenir shopping, they spy Arata buying a present for the boy she likes, and Yuu asks Mato if she wants a boyfriend. Mato tells Yuu that it's too soon and she should wait until high school, and Yuu teases that it's fine since she has her "Tiny Bird" for now.

Once they return, Yuu and Mato see Arata become publicly shamed when her love letter is posted to the school. They both wonder why Arata is hiding her pain like that, and cry together.

Later no one seems to remember her, except Mato. When Mato finds her back where she remembers where her house was Yuu reveals that the otherworld and the otherselves do exist. She sends Mato to the Otherworld to become Black★Rock Shooter, and save Yomi. Yuu and Mato enjoying coffeeAfter Mato is trapped in Black★Rock Shooter, Yuu insists that Saya allow her to follow Mato. Yuu transports herself to the otherworld and enters Strength's body and tries to help free Mato, but is overpowered by the enraged Strength. It is then revealed that Yuu is actually Strength, who switched places with the real Yuu sometime before meeting Mato.

As Yuu, Strength's body is found by Saya near the river and brings her back to the house. Strength is seen, again, in the otherworld attempts to sacrifice herself to save Yuu and Mato, but is stopped by the fight with Insane Black★Rock Shooter. Strength is able to calm down Yuu, but slowly begins to break apart. Later, Mato finds Yuu and Strength. Mato cries with Yuu as Strength insists she calls her by her real name, Strength. Strength tells Yuu, who says she doesn't want to be alone in reality, that she is her soul and will never be alone. Strength dissolves in Yuu's hands.

The real Yuu wakes up back at Saya's house. Saya hugs her and happily cries over the fact that she's okay. Yuu looks over and sees that Mato had already left. Yuu returns to school as a new student, seeing as only Mato remembers her, and instantly assumes the worst, but she notices Mato smiling at her and smiles back. Yuu is then seen joining Mato, Yomi, and Kagari for coffee with Saya and with them on the roof of the school.

All Information received from:
http://blackrockshooter.wikia.com/wiki/Yuu_Koutari#Gallery