Hagi

Hagi (ハジ Haji) is Saya's first, and only living, Chevalier.

Meeting Saya
In 1870, Hagi was purchased by Joel and Amshel from his parents for a loaf of bread to be a companion for Saya, with hopes that they might mate and create more specimens for future experimentation. Hagi meets Saya who was apparently a spoiled child. Although ordered to follow her each and every orders constantly, he showed stubbornness at first. But when Saya listens to Hagi's story, she shows sympathy and reveals her friendly side. Hagi clings to this and their relationship develops.

Life in the Zoo
Hagi lives with Saya in Joel's mansion for many years, him growing up but her never aging. By this time, he and Saya have become quite close. He asks Joel about Saya and why she never grows. Joel reveals that Saya is special because of her blood.

Becoming Chevalier
In 1883, he falls from a cliff attempting to pick a flower that Saya wants as a present for Joel's birthday. Misunderstanding an earlier conversation between Hagi and Joel about why Saya lives on blood, and wanting to save him, Saya feeds him some of her blood, unwittingly turning him into a chevalier. Requiring blood to feed, Hagi transforms fully and kills many in front of Saya. The terrified face of Saya compelled him to take the oath of not transforming or taking blood.

Saya feels some guilt over this through the years, but when she apologizes, Hagi assures her that he has no regrets as it allows him to always be at her side while she lives her dream of traveling the world with her sword.

After the Duel Ends
After Diva's death, Hagi convinces Saya to live, confessing that he has always loved her. Agreeing that she does wish to live, Saya kisses him. As they, along with Kai and the rest of the Red Shield operatives, try to escape the opera house, Amshel attacks them, ripping off one of Hagi's arms. Saya reloads her sword with blood and is ready to fight him to protect Diva's babies. However, Hagi takes her sword and pushes her aside so she can escape while he impales Amshel himself. As Amshel crystallizes, he stabs Hagi through the chest and the ceiling collapses on them both. He tells Saya that he'll always love her. Saya screams his name before they leave. She believes he may be dead, but Kai reassures her that Hagi will return.

Watching Over
Sometime after Saya goes into her hibernation, Kai brings Diva's daughters to visit the Miyagusuku crypt where Saya is sleeping. When they arrive, they find a fresh pink rose with Hagi's blue hair ribbon tied to it. Hagi is alive and he is watching from afar, waiting patiently for his love to awaken after her thirty year sleep.

Skills
Hagi plays the cello, a skill he learned from Saya and later surpassed his teacher. He usually carries his cello in a large black case.

Special Abilities
Feeding: As with most chevaliers, Hagi doesn't need to eat or sleep, and he stays awake while Saya eats, sleeps, or goes into long periods of hibernation.

Blood Attributes:
 * Regeneration: Hagi's blood is capable of healing self wounds. However, if the wound is inflicted by the queen who has made him chevalier, the regenerated part is likely to take permanent chiropteran form.
 * Awakening/ Strengthening Queen: Saya was forcefully awakened during the Vietnam war by injecting Hagi's blood. This indicates that Hagi's blood is a source of his queen's chiropteran strength. It can awaken her chiropteran mode. Saya is shown to consume Hagi's blood several times.

Transformation: Unlike Diva's chevaliers, Hagi never makes a full transformation into a chiropteran form; however, this is by his own choice rather than a limitation of his power. He keeps his right hand bandaged most of the time to hide the fact that its form is permanently chiropteran since Saya injured it while going crazy from being forced awake decades ago in Vietnam. In the opening credits of the final season, Hagi is shown with bat-like wings, but he does not use them in the series until Episode 43. One of his wings is torn by Amshel during the fight on top of the Chrysler Building.

Weapon
Hagi uses the cello-case as a blunt weapon and a shield, and the case also holds Saya's sword. He also fights with a handful of silver daggers that he keeps with him.