Saya is the name given to an extradimensional alien brought into this world the experiments of Dr. Ougai, a Japanese doctor working for the Tokyo University Hospital.
Saya initially lived with Ougai, until she got loose in the hospital, feeding on cats, and eventually human infants. She eventually meets Fuminori Sakisaka in the hospital, who, because of brain damage from an accident, saw her as a normal girl, but saw everyone else as horrific monsters and everything as covered in blood and gore. Fuminori fell in love with Saya, and under her influence, discovered a taste for human flesh. Saya and Fuminori go onto killing several people including their neighbours and one of Fuminori's friends, a woman named Oumi Takahata.
Her ultimate fate depends on the decisions made by Fuminori. She either dies at the hands of Ryoko Tanbo, who dies of her own wounds shortly after, or by spreading her spores through the Earth causing humanity to turn into her species. If she cures Fumonori of his insanity, she leaves, not wanting him to see her true form, and briefly visits him after he got put into an insane asylum before leaving to search for Ougai.
Battles here were deemed to be unfair or otherwise not in accordance with wiki standards, and have been removed from the statuses of the warriors and displayed below.
Battle vs. Flood (by SPARTAN 199)
"Saya" walked into the Flood-infested Covenant Holy City, High Charity. Saya stood on the roof and crept up on a Flood Tank Form that was unaware of her presence, before she lunged at the Flood and thrust the claws at the end of her tentacles into the creature.
The Flood Pure form was merely angered and knocked Saya off it, throwing her across the room, on the Flood Biomass-covered wall. Saya was minimally injured by this and got up, taking aim at the Flood and spitting a stream of acid it at the Flood Tank Form.
The Flood Pure Form transformed into a Stalker Form shortly before Saya spat her acid, the acid stream going over the head of the new, shorter Flood Form. The Stalker form lunged at a Saya, pinning her to the floor and biting at her with its sharp teeth.
Saya flattened out her body and slid under the Flood Pure Form and attacking it with her claws, tentacles, and teeth from behind. The Flood Stalker form jumped again, dislodging Saya's tentacles as it went. As Saya regenerated from the damage caused by the Pure Form's attacks, the Stalker Form climbed onto the ceiling.
The Stalker Form transformed into a Ranged Form. The Ranged Form fired a hail of spikes with the force of bullets. Saya was perforated by the attack, tearing through her flesh. It would take her a while to regenerate from this.
Saya spat another stream of acid at the Flood Pure Form. The acid made a hissing sound as it burned the alien's flesh. The Flood Pure Form was wounded, but not dead. The Pure Form transformed into a Tank Form, jumped to the floor and charged at the wounded Saya.
The massive clawed hand of the Tank Form slammed into the smaller alien, its claws cutting into her flesh. The Tank Form slashed at Saya again and again, striking her with its claws and stomping on her until she as torn clean in half. The two halves of "Saya" lay motionless on the floor as the Flood Tank Form roared in triumph.
The battle was declared unfair for Saya because she was out numbered by the three Flood forms.
Battle vs. Lucy (by SPARTAN 119)
Lucy walked into an abandoned house, an MP5 she had taken from a dead soldier in her hands. Lucy walked down a corridor into the living room, filled with battered furniture. Suddenly, something slid out from under the couch, a space of less than an inch. The creature looked like an amorphous mass of tentacles, with sharp claws on the end.
Saya struck with a clawed tentacle, cutting a gash in Lucy's side and knocking the MP5 out of her hands. Saya then pushed Lucy down with her tentacles and said something in a scratch voice with sounded something like "Don't struggle, I will all be over soon".
"Yes, it will", Lucy said, "FOR YOU!". Lucy lashed out with her vectors, slicing off several of Saya's tentacles and knocking her backwards.
Saya got back up and shot back with a stream of acid. Lucy raised her vectors, blocking most of the acid, but a small amount got on her stomach, burning right through her clothing and into her flesh with a hissing sound.
Lucy ignored the pain, what little acid had gotten onto her had only burned a shallow hole. Lucy grabbed the MP5 with one of her vectors and pinned Saya to the ground with another. Lucy then emptied all 30 rounds into Saya's body.
For good measure, Lucy then thrust her vector's into Saya, then pulled them out in opposite directions, causing her body to explode, covering the walls with pieces of her body.
Lucy walked away from the room, turning her back on the stains on the wall that had once been Saya.
WINNER: Kaede "Lucy"