Riku Miyagusuku

Riku Miyagusuku (宮城 リク Miyagusuku Riku) is the adopted brother of Kai and Saya, the youngest of George Miyagusuku's three adopted children and Saya's second chevalier.

Appearance
A good-looking boy whose apparent age is 14 years old, Riku is 4'3" (130 cm) in height and weighs 85 lbs (38.5 kg). He has neatly-combed brown hair with a fringe and brown eyes. After his transformation, Riku wears black suit given by Joel VI, similar to Haji's and Solomon's attire.

Personality
Even though the youngest of the Miyagusuku family, Riku is shown to be more mature than Kai, his elder brother.

Riku is a very kind and intelligent boy. He loves to cook. His gentle nature even rubs off on the reclusive Hagi to some degree, particularly after he brings Hagi a plate of food and asks him to join the others. Hagi teaches Riku how to play the cello and protects him from a bad injury after Riku falls from a moving train.

Skills
Cooking: Riku is a good cook and he helps his dad around the Omoro kitchen.

Music: Hagi teaches Riku how to play the cello. Although he has trouble at first because his hands are short, Riku gets the hang of it.

Sports: Riku has no particular interest in sports. But he used to practise pitching as pass-time with his siblings when George was alive. Before his death, he bought baseball gloves and played catch with Saya and Kai in an attempt to bring them together.

Special Abilities
Exceptional Hearing: Even before Riku became a chevalier, he could hear the cries of Chiropterans from long distances and also Diva's singing. This ability caught the eye of Van Argiano first and he decided to capture Riku for delta experiment. Diva's song affects him more than others which even intrigues Diva to develop a special interest in him after they met in the Zoo.

Developed Strength: Being a chevalier enhances his strength though not near Hagi's level.

Regeneration: He gains regenerative abilities, as seen when his shoulder heals almost instantly after a Schiff injures it.

Feeding: Riku does not need to sleep or eat solid food and develops a detest for both. Instead, he results in developing an unquenchable thirst for blood. After the schiff attacked Red Shield ship and a Red Shield guard's dead body lied in a pool of blood, Riku couldn't control himself from approaching to drink the blood. It resulted in Kai letting his younger brother feed on his own blood.

Transformation: Like Solomon, Riku uses a partial transformation of his right hand which transforms to a reddish blade to fight. He asked Solomon to teach him how to do it.

Life in Okinawa
Riku leads a normal, cheerful life in Okinawa with his adopted father, brother and adopted sister. After their father's death, he accompanies Saya on her journey to slay chiropterons.

In Vietnam
Riku accompanies his brother and sister to Vietnam. With Saya gone to the Lycee, he finds himself passing time with Kai. He wanders around in the neighborhood, meets other children, plays with them. There he meets a girl around his age called Mui who can also hear chiropterans like he does. He and Kai save her once, stay in the orphanage where she stays and get kidnapped. After they break out of the prison and reunite with Saya, Riku's friend transforms and is taken away.

At the Zoo
Riku goes to the Zoo with the other Red Shield members. He is left alone as others spread out to search for Saya. Then he hears Diva singing and getting drawn by the voice, he soon reaches the tower where Diva was imprisoned long ago. When he reaches the dark cell, he sees a girl and mistakes her for Saya. As soon as Diva's eyes glow bright blue, he realizes that she's someone else. But he is too late to escape Diva who starts draining his blood as he lets out a scream.

Becoming a Chevalier
After Diva drinks most of his blood at the "Zoo", Saya is forced to turn Riku into a chevalier to save his life. Afterwards, Riku shows a compulsion similar to Hagi's to protect Saya at any cost. Despite a brief estrangement, Riku remains close to his older brother Kai and works to heal the broken relationship between Kai and Saya after Kai learns the truth about her.

Rape and Death
Draining Riku's blood seems to cause Diva to develop a strong interest in him. She takes Karl to the Red Shield Headquarter to find Riku. Once she finds him, she raped him then kills him with her blood. In the light novel adaptation, it's explained that something in Diva's eyes causes the Chevalier blood in Riku to react with a "maddening desire" that causes him to be incapable of escaping or physically resisting Diva's actions.

After Riku's death, Kai has a piece of his crystallized body made into a pendant, which he wears around his neck to remember his lost brother.

Season 1
Riku spends his everyday life putting up with his sister's everyday ruckus on waking up late and rushing for school. He has been recently wishing to see the rumored cello-guy who is supposed to be traveling in search of someone. One day, after school hours, he is bullied to a corner by thugs sent by Mao. Saya rescues him and they break for a run. Then they come across the cello-guy who suddenly reaches out for Saya. Horrified, they run away again.

Later, Riku is nearby a gas station when Saya is forced to fight a monster after a force-feeding of blood by the cello-guy. Suddenly, the gas station explodes, injuring Riku badly. He is admitted to the local hospital and watched over by Julia, a doctor and Red Shield agent. During his unconsciousness, Saya learns the truth about herself - that she is not a human.

Season 2
Riku is kidnapped by Charles, who leaves a message engraved on Julia's chest for Saya to visit Vietnam to find Riku.