He's the Sacrifice Unit of Breathless. He’s the stronger one of the two and since he is Ai's sacrifice he gives her strength with his encouraging words and with his strategies on how to best defeat Soubi.  Once they are ordered to stop trying to retrieve Ritsuka, they talk to him and warn him not to trust Soubi, but are sent back home to finish with their own schooling. They are very close and don’t like to be separated. Their names are on the palms of one of their hands.  (Source: Novellalive and Angel Fire)

Twelve-year old Aoyagi Ritsuka is left with his insane mother as his only family when his brother, Seimei, is killed suddenly. After moving to a new school, he meets Agatsuma Soubi, who claims to have known his brother. Ritsuka eventually discovers that Soubi and Seimei used to be a fighting pair, whereby Soubi was the "Fighter" and Seimei was the "Sacrifice". Now that Seimei is gone, Ritsuka has inherited Soubi, who will become his "Fighter". After learning that Seimei was killed by an organisation known as the "Seven Moons", Ritsuka decides to investigate into his brother's death, with the sometimes useless help of Soubi, along the way.
 
(Source: Anime News Network)

__Agency:__ I'm Enterprise

[Profile](https://www.imenterprise.jp/profile.php?id=55)

Has a younger sister.

Ricardo Richter is the son of Peter Richter and Astrid Richter. His brother Raúl Richter is also an actor and voice actor.

Aoyagi Ritsuka is one troubled 6th grader. Two years ago, he mysteriously lost his memory and developed an alternate personality. His mother constantly berates (and occasionally beats) him, asking what happened to the "real" Ritsuka, and his only defender and friend, his older brother Seimei, was recently killed. 
Suddenly, Seimei's apparent "friend," Soubi, appears. Soubi tells him that Ritsuka's true name is "Loveless," and that Soubi was assigned by Seimei to take care of Ritsuka and protect him. Ritsuka soon gets sucked into a bizzare underground society where teams of people, a "Fighter Unit," and a "Sacrifice," battle using elaborate and beautifully-phrased spells. 
He seeks both acceptance of himself, and the answer to the mystery of who killed his brother and why. 
(Source: Tokyopop)

Midori Arai