Yui (ユイ, Yui) is a big fan of Girls Dead Monster, also acting as an assistant for publicity and other matters. She became the lead vocalist after Iwasawa disappeared. She had sung "Thousand Enemies" as a lead vocalist while the other song, "Shine Days", was not fully sung in the series, but only its chorus. Her singing voice is LiSA. She's one of the heroines of Angel Beats! -1st beat-.
Yui has long, pink hair with two bunches tied up with dark red laces, and two twintails on the sides of her face, held together by small cross-shaped barrettes. Her eyes are hot magenta. She wears the same uniform as Yuri and the other girls, although her shirt appears to be small enough to see her belly. She wears crossed black ribbons up to her knees and black boots. Though they don't seem to be in use, she also wears garters on each thigh with the addition of black choker around her neck.
On her wrists she sports single handcuffs with few slabs remaining on each (possibly, both parts formed a common pair of handcuffs). She wears wings that are hidden behind her hair. Another particular trait of her is her "demon tail" which seems to twitch and move whenever she is excited, happy, or emotional in any way. She also has two pointy teeth like a cat.
Yui is extremely bright, cheerful, crazy and even a bit wild. She is known to be hyperactive and talks extremely fast. Even within the members of the SSS, she comes off as very excited and loud. She is often flirtatious with others, and takes advantage of every opportunity she can. She usually tells the other SSS members that they're "morons", mostly because under the surface she is actually quite intelligent. She is also a huge admirer of Hisako, because of her 'murderous' guitar gift.
Her upbeat personality is most likely inspired by her past life in the living world where she was paralyzed since she was four years old from head to toe.
In the living world, Yui was hit by a car when she was four years old. Due to this, she was paralyzed from her neck down ever since and has been taken care of by her mother.
Within the indefinite time she stayed in her room, she was usually seen watching television. Seeing different things on television became her only pastime, and she once wished of doing the things she watched when she manages to recover. Unfortunately, that time did not come.
It is unknown how she died, but it can be assumed it may have been due to a quadriplegic complication, or that her body somehow broke down in some way. In the afterlife, she is ecstatic to have full mobility and rejoices in being able to do all kinds of things she had never even dreamed of before.
After Iwasawa's departure, Yui assumes her place in the band as the lead vocalist.
Upon being introduced to the SSS, she instantly gets along with Hinata, whom she usually gives a variety of wrestling holds to. Hinata always returns the favor, and at one time, he initiates the exchange. She was only seen performing "Thousand Enemies" as a diversion for "Operation Tornado". Although the only GirlsDeMo member (after Iwasawa's disappearance) to be in the Anti-Angel Headquarters, she does not contribute much in the missions, except as a diversion squad.
As the series progresses, Otonashi was able to fulfill her regrets. He helps her by doing the German Suplex, playing 5-on-1 soccer game (Maradona) and playing baseball (though she doesn't hit a homerun). After telling Otonashi that her last regret was marriage, Hinata later helps her fulfill her last regret by proposing to her, and giving her a vision of what could have been had they met in the real world. They'll meet when Hinata breaks Yui's window with a baseball, then he'll come and retrieve it and he'll start visiting more frequently, finally even relieving her mother of her duty to take care of her and they'll marry sometime after that. After thanking Hinata and Otonashi, Yui disappears, having fulfilled her regrets and moved on, leaving only her baseball bat and the baseball helmet she was wearing at the time.
- Yui has little combat ability to the point even Yuri does not rate her as an effective threat against Angel, merely as a general distraction. However in non-combat situations, she displays surprising ability in wrestling (her favorite is "German Suplex " and she did this to Otonashi). She has caught Fujimaki with a heavy kick in a soccer game and Hinata in the second Guild Descent Operation.
- In the special opening credits focusing on Yui (and which doubles as Yui's audition performance), she is playing a Gibson SG Special.
- Yui is very similar in appearance to Etna from the Disgaea series.
- It seems that she doesn't know Naoi as what she stated on Episode 08.
- The song played during the scene where Hinata helped Yui to fulfill her last achievement (get married) was "Ichiban no Takaramono", which was later re-used in Episode 13 (Otonashi confessed his feelings towards Kanade), albeit with slight modifications like the song being played on piano rather than guitar and a different singer.
- Her back story seems to be a reference to Taiyou no Uta, a movie that the singer YUI starred in.
- The title of the episode Yui dissapeared in is "Goodbye Days" which is also the title of the main song YUI sings in Taiyou no Uta.
- Yui's dolls, in her bedroom in back story on Episode 10, come from 'Air' and 'Clannad'.
- She has the same english voice actor as Fuko Ibuki from Clannad and shares a similar personality and story as Fuko.
- Like some of the Angel Beats girls, Yui entered Saimoe Contests.
- To see here result, visit here: http://saimoe.wikia.com/wiki/Yui
- "Even death can't cure idiocy."
- "She's a moron, right?"
- "This world has no cops. Just get a bat from the baseball club. Now off you go!"
- "I'll keep singing for everyone, even when I'm wetting myself! I'll show you what I got!!!"
- "They're all morons!"
- "Yea, Yea. I saw the whole thing. That's why I've come to offer my help, Mew."