Ren Kiryu

Ren Kiryu is the only son of Yuki Kuran and Zero Kiryu. His is an aristocrat due to his mother being a Pureblood vampire and his father being an ex-human vampire. Ren appears at the end of Chapter 93 with his older half-sister to give Yuki's final message to Kaname when he wakes up from his 1000 year slumber. Along with his mother's cousin Senri, he is one of the only known aristocrats descending from the Kuran Family.

Appearance
Ren appears to be physically a teenager. He has silver hair like his father Zero and red-brown eyes like his mother Yuki. Ren is also frequently seen dressed similarly to Zero in the manga.

Personality
While his interactions are limited in the extras, he has been shown to have a calm demeanor and will speak up whenever his sister has difficulty expressing herself. He appears to have a good typical sibling relationship with Ai as they both are shown scolding one another. While calm in nature like his father, Zero, Ren does not appear to have Zero's stoicism as he is shown smiling and joking around with Ai. However, while he seem to have inherited his playful side from his mother, Yuki, his blunt nature definitely resembles a teenage Zero as he states whatever Ai has difficulty expressing.

Story
Ren appears at Kaname's resting place along with Ai and their mother Yuki. He and his sister watch their mother give her life to Kaname to turn him into a human. Ren finished Ai's phrase that she passed as a message from their mother to her father "I want to give to you, whom I love, the world that I saw when I was a human".

Ren was born after the events in the extra chapter Life.

In the extra I Like You, Ren and his sister Ai in the end told Kaname the story of the last thousand years, but Kaname had lost much of his memory that he wasn't responding to anything they were saying. As he laid down on the ground, Ai began saying that she did not want Kaname to live the rest of his life not remembering his past. At this point, Kaname embraces them both and asked them to tell the story of the past millennium once again.

His name was revealed in third extra chapter.

In the fourth extra chapter, Between The End Of Life And Heaven, Ai had told Ren that they weren't supposed to tell Kaname that Yuki "exists inside of him," but Ren did not regret mentioning any of it for he wanted to see Kaname's reaction. Ren then says that even though there was no point in shaking him up, they couldn't help but bait him despite the fact that Kaname has no memories. Ai then proceeds to wrap her arms around Ren's arm and tells him that they don't know what Kaname is thinking or feeling, that Ren wants to understand that by just observing him. Ai mentions that she has heard things about Kaname from Yuki and Zero but she still cannot believe them, to which Ren responds with a "there must be things you don't want to believe." Ai takes note of Kaname listening to them closely when they speak, that once in awhile he'll ask a question and when they answer him, Kaname becomes silent and listens to them again, to which Ren agrees. Ren then says that they are glad that Ai was not disappointed when meeting her father because they were thinking that he might have a disagreeable nature. Ai tells Ren that they themselves have been thinking that they might dislike Kaname to which Ren replies with a serious face saying "I'm still not sure.." That all he thought was that Kaname's hand was very gentle. They both then realize that they've been reflecting too much and Ren asks if they should go back and talk to Kaname again. Ai agrees and says she doesn't want to leave him alone either because from what she's heard, Kaname gets lonely very easily.

Trivia

 * Ren's name has a similar meaning to his sister, Ai. While Ai's name represents affectionate love, Ren's name is written with the Kanji which is associated with romantic love (恋, koi).
 * Despite being referred to as 'he' in the English translation and 'she' in the French translation, it is currently not known what Ren's gender is. When Ai introduces Ren to Kaname in the third extra chapter, she refers to Ren as her キョウダイ (kyoudai), which means sibling and is non-gender specific. However, it has been noted that Ren typically uses a masculine speech pattern in Japanese.