For those who wanna know and don't mind spoilers for an old game, well here's what I remember: Her full name is Kirishima Mana, she appears in Shinji's class all of a sudden and she appears to be in love with him. They went on a date and all(Asuka was surprisingly jealous of her). But in the end she turns out to be a spy sent from some government agenct(don't remember which country) who appears also building large machine to battle the Angels. The sent Mana to infiltrate NERV and Shinji was simply her stepping stones to get into the NERV hq. Her feelings for Shinji is decided by 3 options in the game. Option 1, She had a short talk with Shinji before she was taken away by the agents who sent her, apparently she have no feelings for him (though I believe she's trying to hide her feelings to leave Shinji out of this)... Option 2, Her feelings for Shinji appears to be true, and they spent 1 precious day with together before she parted, to live on as another identity in another place. All to ensure that the agents can no longer track her down and She and Shinji will never see each other again. Options 3, Shinji chose Asuka (dun remember the details)...
