Yuu Koutari is one of the main characters of the Black Rock Shooter anime.
Yuu is a childhood friend of Mato who often skips classes. She is also fond of coffee. She is in fact Strength, having switched places with the real Yuu years before the beginning of the show. As such she is not entirely real, though she can still interact with the physical world.
In the AWA fics, Yuu is a student at the AWA Academy and is a part of Class 23.
Yuu has combed down tawny hair and hazel eyes. She wears a white dress shirt with a blue ribbon tie, dark-blue skirt, a white socks with small pink ribbons and brown shoes. She also wears an orange hairclip on the left side of her hair.
Yuu is excitable and perky; she is also eager to tease Mato often. 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. The real Yuu was great friends with Saya when she had her problems and went to her house almost everyday, making Saya the first one to know about the secret of the other world after Saya apologized for accusing Yuu for burning down her house when it was her stepfather's cigarette.
Yuu is likely has the same ability as Mato Kuroi and Yomi Takanashi in transforming into her otherself.
- Yuu alongside Mato Kuroi, Yomi Takanashi and Kagari Izuriha are the first characters from Black Rock Shooter to be introduced in the AWA fics.
- In the anime series, Yuu, as Strength, is one of two characters to face B★RS/iBRS in a fight and not die. The other is Mato, who was disguised as Black★Rock Shooter. Black★Gold Saw also survived iBRS's wrath, but only because Strength saved her.
- In the anime series, it was revealed in Episode 6 that Yuu, even before switching places with Strength, knew a lot about the Otherworld, or at least of the "other selves".
- In the anime series, Yuu has no shadow. This is because the real Yuu was in the Otherworld, while Strength was in the real world.