Sin

Abyss' female partner, who is as strong as he is, and seems to be aware of a link between Shizuno Misaki (Yehl) and Gards-orm. Sin manages to infiltrate the Oceanus with a childlike desire to understand why the Celebrants continue to fight, specifically questioning Minato, Lu-Shen, Kyo, and Ryoko. When Ryoko presents her an answer she particularly likes, she transfers part of her data to Ryoko to restore her apparition, though Ryoko's emotional component data remains trapped in the Altair. It is through Ryoko that Sin begins to understand what it truly means to be human, though she fails to fully grasp human values.

(Source: Wikipedia)