elfen lied - Who was this girl by Lucy in special episode 10.5

In special episode 10.5 of Elfen Lied anime, there was a scene where Lucy was together with a girl in a school. Who was that girl? A friend? And why did she want to protect her? I thought Lucy hate

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Elfen Lied Lucy by BenjiRivera1991 on DeviantArt

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Pin by Stefanno Diaz on Kyou no Asuka Show

Elfen Lied - Wikipedia

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elfen lied - Did Lucy ever recover her consciousness? - Anime & Manga Stack Exchange