Ren Kiryu

Ren Kiryu or Ren Kuran is the only daughter of Yuki Kuran and Zero Kiryu. Due to her mother being a Pureblood vampire and her father being an ex-human vampire, she is a Aristocrat. Ren appears at the end of Chapter 93 with her older half-sister to give Yuki's final message to Kaname when he wakes up from his 1000 year slumber. Along with her mother's cousin Senri, she is one of the only known vampires from the Kuran lineage to not be a Pureblood.

Appearance
Ren appears to be physically a teenager. She has silver hair like her father Zero, however her eye color is reddish brown like the others in the Kuran family; though some artwork shows her eyes to have a tinge of lavender like Zero's. Taking after her father Zero in looks, Ren has a rather gender neutral appearance. Due to this and her preference more gender neutral clothing, Ren can easily be mistaken for a male.

As a child Ren had long hair and was dressed in dresses by her sister, Ai. During her days in the Night Class, Ren greatly resembled their mother Yuki despite her sliver hair. By this point her clothing tastes had started to be less girly, as aside from her Night Class uniform, her pajamas were a shirt and pants.

Ren is shown to be taller than Ai as an adult.

Personality
Ren has a calm demeanor and will speak up whenever her sister has difficulty expressing herself. While calm in nature like her father Zero, Ren does not appear to have Zero's stoicism as she is shown smiling and joking around with Ai. However, while she seems to have inherited her playful side from her mother Yuki, her blunt nature definitely resembles a teenage Zero as she states whatever Ai has difficulty expressing. Ren also inherited the kindness of both her parents, never wishing harm on others. Ren's kindness is best exampled by staying at the Moon Dormitory instead of her home to keep distance from Ai when she craved her sister's blood.

Unlike Ai, Ren knows what a "job" is, even explaining what one generally is; the topic came up when Kaname considered getting one, until Ren informed him that the Kuran family has wealth and resources. Ren knows about this due to attending Day Class in her childhood. Thanks to this, Ren also has experience cooking, as opposed to her sister. Even as a child, Ren showed a good deal of common sense, as she promised her mother to not reveal her true identity to her classmates or take energy from them in exchange for attending Day Class

Thanks to Ai doting on her as a child, Ren is very close to her older sister. Even as a child, Ren showed an interest in the role of protector as she would take the role of "knight" when she played dolls with Ai; she spent more time with Zero to learn how to use a gun, because she wanted to protected others with her own. When she got her fangs, Ren stayed away from Ai because she craved her blood (ironically enough) and the very thought of draining her dry scared her; she would dream of it, only worsening her self-hatred, as she had promised to protect her sister. She hates to remember this time in her life, because it was when she felt the most helpless.

Ren was never bothered by other vampires holding a low opinion of her due to her father being both a hunter and a "common" vampire, as opposed to another Pureblood. It only affected her when a vampire would insult her in front of Ai, who would snap ferociously at the vampire in question.

Story
Ren appears at Kaname's resting place along with Ai and their mother Yuki. She and her sister watch their mother give her life to Kaname to turn him into a human. Ren finished Ai's phrase as she passed as a message from their mother to their "other" 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 her 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.

Her name was revealed in third extra chapter, however her gender, which had remained ambiguous, was not revealed until chapter eighteen of Vampire Knight Memories as female. It has not been explored of what her gender identity is.

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 she wanted to see Kaname's reaction. Ren then says that even though there was no point in shaking him up, she 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 her 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 she is glad that Ai was not disappointed when meeting her father because she was thinking that he might have a disagreeable nature. Ai tells Ren that she herself had been thinking that Ren might dislike Kaname, to which Ren replies with a serious face saying "I'm still not sure.." She states  that all she 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.

Zero Kiryu
Zero Kiryu is Ren's father. As a child, Ren is shown to idolize her father and was constantly chaperoned by Ai when she went to observe his time at the shooting range. She takes after Zero's coloring through the notable silver hair each Kiryu is known for and in certain artworks she is occasionally shown with lavender eyes. Ren had a loving childhood and was seen being doted on by her father very much making her a daddy's girl. Ren has Zero's blunt nature and has shown occasional sarcasm but it's not as cynical as Zero's can be when he's annoyed. She is shown to have similar reactions as him when not amused and tired. During the turmoil of the emerging Vampire King, Ren takes it upon herself to pursue becoming a Hunter in order to protect those she loves and to protect Ai from having to intervene in saving Ren again after an accomplice of the Vampire King nearly detonated a bomb located inside a choker placed on Ren's neck.

Yuki Kuran
Yuki Kuran is Ren's mother. While Ren may have her father's coloring she shares a strong resemblance to her mother during her time at Cross Academy. Ren also trims her hair in a similar bob as her mother's as an adult. Ren is shown to take after her mother when it comes to showing some cutesy moments of interacting with fellow classmates and teasing Ai. Yuki is seen cradling a baby Ren and possibly went along with Ai in dressing Ren up in girly clothing in her childhood. Ren chose to initially start school in the Day Class before her vampire traits emerged causing her to transfer to the Night Class similarly as her mother.

Ai Kuran
Ai Kuran is Ren's older half-sister. The two have been inseparable since the moment Ren was born. Ai had been looking forward to having a younger sibling and pestered her parents daily to have another child. Upon discovering her mother's pregnancy Ai is thrilled and spent all her time assisting a pregnant Yuki. At times Ai appeared to display some maternal traits and doted on her younger sibling in some instances in a motherly manner. Ai was known for dressing Ren up in girly dresses and kept a constant monitor of her younger sister whenever she left for school. Ai took it upon herself to pose as a guard and secretly hide in the shrubs to watch her sister interact with classmates (Ren always noticed her sister and did not appear perturbed by her sister's daily ritual).

As time went on, Ren's vampire traits emerged causing her thirst for blood to intensify. She was horrified at the thought of harming Ai whom she wished to devour and become "one with her lovely older sister." Ren did not realize that Ai was okay with this and had been waiting for the moment they could provide one another with blood. Ai was not bothered by Ren seeking her out for blood after an accomplice of the Vampire King almost killed Ren. Ai is very protective of Ren and was easily angered whenever the Purebloods or Aristocrats sneered at Ren for what they thought was polluting the Kuran bloodline since she was considered a half-breed. Ai has occasionally lashed out at vampires who mock Ren but is easily calmed when Ren intervenes to stop her. As Ren grew older it's been left ambiguous as to the relationship between Ren and Ai being familiar or romantic in context. The two are often shown in affectionate gestures more akin to lovers than sisters so there is a strong possibility the two develop a romantic relationship in adulthood. In the Kuran bloodline incest is not frowned upon and has become a habit overtime. Therefore, it is up to the readers' discretion on whether Ren and Ai remain as close sisters or as lovers.

Trivia

 * Ren's name has a similar meaning to her sister, Ai. While Ai's name represents unconditional love, Ren's name is written with the Kanji which is associated with romantic love or crush (恋, koi).
 * Despite being referred to as 'he' in Volume One of the English translation and 'she' in the French translation, it was not until chapter eighteen that Ren's gender was revealed to be female. When Ai introduces Ren to Kaname in the third extra chapter, she refers to Ren as her kyoudai (キョウダイ), which means "sibling" and is non-gender specific. The official English release mistakenly translated this as "little brother." They later reprinted the volume to change the translation to "sibling."
 * Aoi Yūki voices Ren in the Drama CD which came with volume 4 of Vampire Knight Memories.