Yuki Saiko fights the Lucifer Hawks in the Silent Mobius anime and manga series, as a member of AMP. For the most part she does not directly become involved in the fighting, providing a support role for her colleagues.

She is product of an ESPer project, where unlucky orphans had their genes taken and implanted in others, increasing the successful candidates powers considerably. She has great abilities that she can wield when necessary, killing a Hawk that attempts to trap her in the past in one episode.

Yuki is very much the baby of the group. She always brings a smile to her friends' faces with her cheerful attitude. However the young psychic is completely innocent when it comes to relationships, though she does have a fleeting romance with a young guy called Toru. However this is only by accidentily being sent back in time to 1999! She also own a shop and makes great coffee, though as an AMP member she can never open it for long enough to get any customers. Toru actually owns the shop (though he is obviously now much older than from when she met him in the 20th century) and does not make her pay rent - she is extremely surprised to realise who he is when she comes back from her trip to the past.

Her relationship with Toru is actually very important to the development of the plot. After she manages to return to her own time, he is approached by a Lucifer Hawk agent. In return for financial success and the chance to see her again, he has to back Maximillian Ganossa's attempts to reactivate the cyclotron that failed the seal the gateway between Nemisis in the first Project Gaia. Though Toru has no idea of what Ganossa is planning, he unwittingly helps bring about the near destruction of Earth. This is very strongly linked to the idea of selling one's soul, though in this case it is for love and not greed.