Otonashi

Saya Otonashi (音無 小夜 Otonashi Saya) is the main protagonist of the series.

Plot
Saya was "born" in 1833 from one of two cocoon-like objects taken from the belly of a chiropteran mummy, the other cocoon containing her sister Diva. Both are kept at the "Zoo" by Joel Goldschmidt, where Saya is treated as his daughter and Diva, who is left nameless, is confined to a tower. Saya does not learn about Diva's existence until 1863, when she hears Diva singing and finds her locked in a room at the top of the tower. Saya then names her Diva. In 1870, Amshel purchases a twelve-year-old boy named Hagi from his parents to become Saya's companion and friend. During a birthday party for Joel in 1883, Saya releases Diva so that she can sing for Joel. Diva, however, slaughters everyone in the Goldschmidt house while Saya and Hagi are out looking for Joel's favorite flower. Recognizing that Diva is a monster, Saya spends her periods of activity hunting Diva to try to kill her, her chevaliers, and any chiropterans they have created.

During a flashback dream she is hunting Diva after the presumed death of Grigori. This takes place after the Russian Revolution. It turns out the girl Sonia is Grigori. Grigori is crystalized after Diva escaping with Amshel. After that Saya goes into her deep sleep(30 years hibernation).

In 2005, when Blood+ begins, Saya is a high school girl living in Okinawa who was adopted a year ago by George Miyagusuku after waking from her hibernation cycle with no memory of her identity or past. Though she appears to be a normal teenager, any injuries she sustains heal almost instantly and she must receive regular blood transfusions to remain healthy. When a chiropteran attacks her school, she finds her life turned upside down. She is reunited with her chevalier Hagi, though she doesn't remember him, and learns that her blood can kill the chiropterans. She is approached by David, from the Red Shield, who tells her it is her duty to kill chiropterans because she is the only one who can. Neither David nor Hagi will tell her the truth about her past, telling her she must remember on her own. Though at first Saya is reluctant to fight and afraid of who she might be, she slowly comes to accept her duty and regain her memories.

After Riku's death, Saya disappears for a year, along with Hagi. When she returns, she has longer hair and a harder, darker appearance. Now accepting of her chiropteran biology, she accepts the necessity of feeding on Hagi's blood to live and be strong enough to fight. However, she has a less cheerful personality, is more morose and less talkative than she used to be. Moses and Lulu both remark that she has lost hope. Believing the fight with Diva is hers alone, and not wanting to have to grieve for any more lost comrades, she avoids cooperating with Kai or the Red Shield. Saya's friends repeatedly work to help her understand that this fight is not for her to bear by herself, and that she is never alone. As the battle with Diva continues, Saya's next hibernation period draws nearer, she starts having sudden bouts of fainting spells, and her regeneration ability slows.

At the Metropolitan Opera House, Saya confronts Diva in a final duel, which ends as they simultaneously pierce each other with their blood-coated swords. Saya is unaffected by Diva's blood, because it lost its potency when she became pregnant. Diva, however, begins to crystallize, and Saya cries for her and tries to hold her shattering pieces together. With Diva dead, Saya turns to kill the babies and herself fearing that if they lived, they would be forced to become military weapons. Kai pleads with her to live, promising to protect her and the babies and make anyone afraid of her understand. Hagi disobeys Saya for the only time in his life, taking her sword and confessing he has loved her from the moment they met. Saya tearfully admits she wishes to live as she kisses Hagi.

A month later, back in Okinawa, Saya finally goes into her next thirty-year hibernation period. At her request, Kai puts her back in the Miyagusuku family crypt to sleep, and he watches over her, and Diva's Children. Several years later, a pink rose with Hagi's blue ribbon is left at the crypt. Hagi is alive and he is watching from afar, waiting patiently for his love to awaken after her thirty year sleep.

Weapon
Saya is a skilled athlete and fights using a special katana with an edge she can touch with her thumb while gripping it so as to draw blood, and grooves specially designed to spread her blood through its entire blade. Once loaded with her blood, it is a deadly weapon against Diva and any chiropteran created from Diva's blood. After Saya's first blade is broken, David gives her a new one that has a red crystal at the base of its blade, symbolizing her membership in the Red Shield organization. The crystal is a piece of her adoptive father's body, which crystallized when she killed him with her own blood in order to spare him the fate of turning into a chiropteran.