Kai Miyagusuku

Kai Miyagusuku (宮城 カイ Miyagusuku Kai) is one of the main protagonists of the series. He is the adopted son of George Miyagusuku hence, Riku and Saya's "elder" brother.

Appearance
Kai is a tanned, athletic teen with brown eyes and average height. He has orange hair throughout season 1 & 2. After the year lapse from Riku's death, his hair is shown to have turned to brown and complexion a bit fairer (probably due to going out only at nighttime Chiropteran hunting).

Life in Okinawa
Once a popular student at school and a star athlete, Kai quits playing baseball shortly before Saya's arrival and has been getting into more fights at school. His debut in the anime begins with him taking Saya on his bike to the hospital so that she can take treatment (blood transfusions). Later he goes to find her at the school, because Saya forgot her track shoes. But there he sees her killing a Chiropteran.

After George was attacked by Forest, Kai seeks revenge on him. He follows Reimi and arrives at a warehouse near a harbor but fails to fight the Chiropteran. Saya finds him at the harbor and kills the Chiropteran that hurt her father. His father's death forces him to mature faster to keep his family together.

In Vietnam
He goes to Vietnam with Saya and Riku, but is left behind in a remote village in Vietnam while Saya goes to investigate in the all girls high school. There he meets Mui, a girl who becomes Riku's friend. He also gets kidnapped along with Riku and Mui and ends up in Karl's mansion in the jungle. He manages to lead Riku, Mui, and other prisoners out of the compound when Saya and Red Shield agents stage an attack on Karl. When Saya loses control and kills some of the Red Shield agents with her, Kai shouts out to stop her. His call brings her back to senses and she regains control over her powers.

Paris
While staying with David and other agents at Red Shield's base in Paris, Kai encounters a girl named Irène who was being harassed by a group of men. Kai saves the girl from them and tries to talk to her, but she is reluctant to have any contact with humans as she has been taught not to trust them. Eventually, she tells Kai about who she is and her condition, the Thorn, which will eventually kill her and her friends. Kai is sympathetic to her, so he goes back to the base and tries to convince Saya to help her. However, Irène's friends, the Schiff, stage an attack on the apartment Saya is staying at after being told by Diva's Chevaliers that they would offer a cure for their condition if they brought Saya to them. The Schiff later learn that this was a ruse to make it easier for the Chiropterans to attack both parties. After their failed attack on the apartment, Kai convinces Saya to give her blood to Irène in an attempt to save her, but this only accelerates her death. The Schiff initially turn on Saya for this, but then come to understand that they had been fooled and that there was no cure for the Thorn. Kai grieves the loss of Irène more than anyone, and it is suggested that the two had fallen in love before her death.

The Truth
Kai learns about Saya's true identity when he reads Joel's Diary. At the Zoo, when Diva drains Riku's blood, he requests Saya to heal his brother with her blood. But as she does so, Riku becomes Saya's chevalier. Kai struggles greatly over Saya, and later Riku, not being human anymore. As he finally comes to terms with both, Riku is raped and killed by Diva. Their failure at the Zoo led Saya to travel alone for a year, hunting Chiropterans without Kai's help.

After Riku's Death
After the destruction of the Red Shield and Riku's death, Kai lives with Lewis and David in an orphanage in London, actively hunting Chiropterans with Lewis and honing his skills as a soldier in the war against Diva and her chevaliers. With David drowning in alcohol and regret, Kai takes over many of his responsibilities in Chiropteran-hunting. Following the tradition of Red Shield, Kai wears a diamond-shaped pendant with a crystal from Riku's remains crested in it. As the last surviving family member of Saya's adoptive family, he has sworn to protect her and return to Okinawa with her once everything has been settled.

When the Feud Ends
After Saya kills Diva, he is able to convince her to continue living, and prompts Hagi to "disobey" Saya and confess his own love for her. Saya and Kai return to Okinawa and reopen their late father's restaurant. A month later, Saya goes into her hibernation cycle and Kai puts her in the family crypt to sleep. Per his promise to Saya, he raises Diva's daughters as though they were his own (though they won't call him Dad). Together, they regularly visit Saya's resting place to keep an eye on her while she sleeps.

Personality
In the first half of the series, Kai is shown to be quite immature and selfish. He is shown to be quite impulsive and turns violent more often when he's pressured. After George's death, he becomes the head of the family and tries to bind themselves together. However, he is over protective of both Saya and Riku. As he struggles within himself regarding Saya after knowing her true identity, Riku similarly goes through life altering changes that only add to Kai's stress. When Riku nearly died after Diva's attack the only reasons Kai could give for making Riku a chevalier were that he didn't want to lose Riku and end up alone. Even after hearing Kai's two completely selfish reasons, Saya still made Riku her chevalier. After Kai had finally come to accept the fact that Saya and Riku are different from him and manages to believe that they can still be a family, Riku is killed by Diva.

Riku's death changes Kai. He faces his responsibilities, hones his skills to be ready, bears the torch of Red Shield to keep hope alive. He believes that Saya will come and his faith pays off.

After the death of Diva and her Chevaliers, Kai adopts her children (as they are his brother"s children as well). As he promised Saya, Kai loved and raised them as his own daughters.

Skills
Athletics: Kai was one of the most popular star athletes in his school excelling in baseball. After sustaining injury in one of his arms, he quits the baseball team and indulges into street fights.

Marksmanship: Initially Kai has little skill in marksmanship, but he improves as the series progresses.



Weapon
After George is attacked by Forest, Kai steals his father's M1911 pistol to seek revenge against Forest. David confiscates it, but later returns it to show that he feels Kai had matured enough to handle it.

After Red Shield's HQ is destroyed, Kai hones his marksmanship skills, practicing with the pistol in the store at Glay's farmhouse. Kai uses it as his primary weapon for the remainder of the series. He also uses Igniter bullets to enhance his shots.

Memorable Dialogues
[Saya is going to kill Diva's children]
 * Kai Miyagusuku: What do you mean you're going to die?
 * Saya Otonashi: We'll surely be used again as weapons of war. I don't want to see another war over our blood. I don't want to see anyone get hurt anymore.
 * [to the babies, raising her sword]
 * Saya Otonashi: I'm sorry.
 * Kai Miyagusuku: Stop it, Saya!
 * Saya Otonashi: We must not live on!
 * Kai Miyagusuku: Don't be stupid! Who decided that? If there's anyone saying you shouldn't exist, I'll kick his ass! And I'll make him understand you're just a normal girl; a crybaby and a gluten!
 * [Hagi blocks Kai from getting any closer to Saya]
 * Kai Miyagusuku: I'll look after you. One way or another I'll find the place where you belong. So just stay with me. Don't you think so too, Hagi?
 * Hagi: I am a servant of Saya. I will do as she wishes.
 * [Kai punches him]
 * Saya Otonashi: Kai!
 * Kai Miyagusuku: Who are you? Be yourself! Just say it in your own words: What do you want? Even you, don't you love Saya?

[Kai is carrying Saya to the crypt where she will have her long sleep]
 * Saya Otonashi: Just a bit more. Kai, thank you.
 * Kai Miyagusuku: There's no need to thank me.
 * Saya Otonashi: Yeah...
 * [she is asleep]
 * Kai Miyagusuku: Saya?
 * [she drops the picture of her, Kai, and Riku]
 * Kai Miyagusuku: Sa-
 * [weeping, he continues to carry her up the stairs]
 * Kai Miyagusuku: Saya, you taught me about the tomorrow that I'm living for. That's why you've been fighting. It wasn't just for your own happiness, but for everyone else's happiness as well. That was all you were thinking about. I promise, I'll make them happy, so-
 * [pause]
 * Kai Miyagusuku: Sleep well, Saya.