In Heaven's Door, she was once a girl who used a pair of scissors to display her intense hatred towards males, responsible for a chain of murders involving the male student population of the Afterlife School. After receiving words of reassurance from Yuri, she joins the SSS as one of its first members after its founding.
Yusa is a girl with long blonde hair tied into two pigtails, each secured in place by a red ribbon. She has red eyes and fair skin. Just like most of the members of the SSS, Yusa wears the standard uniform of the group. She also wears brown stockings and black loafers.
She is always seen wearing an earpiece with a microphone attached to it or carrying a walkie-talkie.
Before joining the SSS, her skirt was longer than the other female students'. Her hair was longer and she left it down, covering her eyes. She always had a sharp pair of scissors to be ready to kill males.
She is a calm and gentle-mannered girl with a straightforward character. Much like Kanade, she doesn't show any emotions and she has been called "scary" by Hinata, Otonashi and Ooyama. She rarely talks, but she sometimes hurts others' feelings even though she doesn't mean it. It seems that she loves her headphones so much that she can't do her missions without them.
When the Battlefront first met Yusa in the manga, she was brutal, slightly unstable and had a strong hatred against boys and men. She tried killing NPC males but wasn't satisfied since they just kept on re-spawning. When she saw the SSS, she saw it as a chance to kill off living males for good and tried to kill Noda and Ooyama, though was disappointed with the fact that they too couldn't die.
It is revealed in Chapter 32 of Heaven's Door that her emotionless personality is a result of using the Angel Player program through the help of Kanade to seal away her violent side. While succeeding in their goal, due to the system Kanade programmed being incomplete, as collateral damage all of Yusa's emotions were sealed.
Virtually nothing is known about Yusa's past, how she died when she ended up in the Afterlife, or what her regret was. However, given the fact that she has a strong hatred against men and would brutally murder them heavily implies she may have been sexually abused by them, a possible clue to her suffering and regret. Upon their first meeting, Yuri realized that Yusa must have lived a horrible life.
Whatever the case when Yusa first appeared in Angel Beats Heavens Door she went on a violent rampage killing most of the male battlefront members in a very brutal fashion. Upon capturing her Yuri tried to recruit Yusa, but she was seemingly too traumatized by the experiences from her previous life to accept. Recognizing that Yusa would prove a handicap to the battlefront Yuri abandoned her recruitment. Following this Yusa approached Kanade, and following a conversation with the Student Council President had her emotions wiped. This left Yusa a calm approachable character, that many people would come to regard as creepy. She then approached Yuri, offering to serve as her operator.
Among the known members of the SSS, Yusa is the only one not shown inside the headquarters, probably because of her job as Yuri's eyes and ears. Yusa herself is never shown to participate in any fights throughout the anime series, an indication that her skill sets are specifically related to observation.
- Yusa has the same English voice actor as Mei Sunohara from Clannad. Mei's older brother, Sunohara, also shares a voice actor with Naoi.
- Yusa was a contestant of the voting contest Anime Saimoe Tournament 2010 but lost to Mizuki Himeji in the first round of the main tournament.
- Unknown to the SSS members, she participated in Operation High Tension Syndrome, although her participation is not noticeable.
- Her name can be translated as "playful assistant".
- She bears a resemblance to Misa Kurobane from Charlotte, also by KEY.