Yuuki Cross's earliest memory is of a snowy night in winter, when she was attacked by one vampire and was saved by another, Kaname Kuran.Yuuki is the adopted daughter of the Headmaster of Cross Academy, Cross Kaien and has grown up and became a prefect for the school with one main purpose: to protect the Human Day Class Students and the Vampire Night Class Students from each other. Her fellow guardian, Zero Kiryu, a childhood companion whose parents were killed by a pureblood vampire, is now determined to kill them all and refuses to trust them. Through a cruel twist of fate, Zero becomes a vampire himself, having been bitten by a pure-blood vampire four years before, Shizuka Hio. Kaname leads the group of Night class as their President, with the help of Takuma Ichijo, the Vice-president.

Yuuki wants to know more about her true family and her forgotten past and starts a research. The secret will be revealed. Yuuki, Kaname and Zero will show the begining of a new mystery and a forbidden love.

Vampire Knight Guilty is very much a traditional shoujo series about forbidden love. However, through the inclusion of vampires, the series takes on a bit more of a gothic feel which is heavily relied on to hold the viewer's interest. T...he story is mainly told from the point of view from the female protagonist, Yuuki, and her inner turmoil about her past and her feelings about the two male main characters, a vampire Kaname and a vampire hunter Zero, are the main driving forces behind the story. The story is also sometimes told from a third-person perspective, allowing the viewer to know details that Yuuki does not. While the story in itself is quite good and probably one of the best gothic romance animes out there, due to the switching of perspectives, the plot pacing can sometimes feel excruciatingly slow and often very repetitive. Yuuki continuously tries to tackle the same issues internally episode after episode to the point where it becomes very redundant; the actual story moves along much better when it is not dwelling on Yuuki's thoughts. This also creates a conflict in the main point of the story, since it sometimes emphasizes the mystery shrouding Yuuki and the other main characters and other times seems to try to hold the viewer solely by building up (almost uneccessary) romantic tension to keep the viewer watching to see which character Yuuki will end up with.

The adoptive daughter of the headmaster of Cross Academy, Yuuki is a member of the school's disciplinary committee, which is also known as Prefect (Guardian). Ten years prior to the events of "Vampire Knight," Yuuki was attacked by a vampire, but was rescued by Kaname. She has lost all memory of her life before the attack because her mother, Juri Kuran, used her pureblood powers to put her vampire side to sleep, and Headmaster Cross took her in as his own daughter. She, like Chairman Cross, believes that vampires and humans can live together peacefully. She has also been giving her childhood friend Zero her blood to save him from becoming a Level E vampire. She and Kaname were raised as siblings by Yuuki's parents, Juri and Haruka Kuran, who were also siblings and heads of the Kuran line of pureblood vampires. She is also Kaname's fiance, whom she believes to be her brother, and Kaname has yet to tell her the truth about who he is. Yuuki loves Kaname, who has always been protecting her and has been by her side during her childhood as a vampire. When Rido Kuran, Yuuki's uncle, resurfaces at Cross Academy, Yuuki awakens her vampiric side and pureblood powers.

A pureblood vampire, Kaname saved Yuuki from an attack by another vampire when she was little. He is the class president of the Night Class, much feared and respected by the other Night Class students. While he is cold and authoritative towards his fellows in the Night Class, he is always kind and sweet to Yuuki. He has shown that he cares deeply for Yuuki, and loves her in a romantic sense. He allows Zero to live because he knows his death would sadden Yuuki, and because Zero is useful. He is both jealous and angry of Zero for biting Yuuki and endangering her life. Kaname has been raised as Yuuki's older brother. At a young age they had pledged to marry each other when they grow up, just like Haruka and Juuri, who were siblings yet married to each other. It is common for pureblood siblings to marry as it is essential to keep the bloodline pure. Also, a fact yet to be revealed to Yuuki is that Kaname is not her "true brother". He is actually the ancient ancestor of the Kurans, and Rido is his master who awakened him from his grave, making him unable to kill his 'master'.

Zero, who is a year older than Yuuki Cross, comes from a vampire hunting lineage. His family was killed by the pureblood vampire Shizuka Hio because of one of the assignments his parents carried out. Zero was taken in by the headmaster of Cross Academy and became a Prefect (Guardian), alongside Yuuki Cross. He has a great hatred for vampires because of what happened to his parents and that he was raised to hunt vampires, though it is revealed that he is a Level E vampire due to Shizuka's attack four years ago. It was believed that Zero was the only survivor of the attack, but it is later revealed that Zero has a younger twin brother named Ichiru who is living by Shizuka's side. Due to a turn of events involving Shizuka and Rido Kuran, Kaname ends up consuming Shizuka, thus becoming more powerful. He then lets Zero devour some of his blood to subdue the Level E vampire side which threatens to take control. Kaname only does this for Yuuki's sake for he does not truly care about his own fate.

Sayori "Yori" Wakaba (若葉 沙頼, Wakaba Sayori?) is Yuuki's dorm-mate and best friend since junior high. Yori is a very perceptive girl who finds the aura of the Night Class to be scary. She is one of the few girls with no interest in the Night Class and not intimidated by Zero, frequently joining Yuuki to tease him while maintaining that Yuuki is the only one capable of dealing with him. Then Yori discovers that Yuuki is a vampire during the attack on the school, but she accepts Yuuki as she is and appears to be more worried over that fact that she would lose her best friend. Because of the recent events at Cross Academy, she is taken to a safe place by Aidou on Yuuki's orders.

Takuma Ichijo (一条 拓麻, Ichijo Takuma?) is the vice-president of the Night Class. He is a noble-class vampire nearly as powerful as Kaname, whom he is close to and respects. With his cheerful and enthusiastic demeanor, Ichijo appears very un-vampire like, lacking the dark atmosphere that surrounds most vampires and making him appear more like a human. His favorite reading material is manga. Ichijo maintains a close friendship with Senri Shiki, whose great-uncle is also a member of the council, and is a good friend to Rima Touya.

Educated by a grandfather with high expectations for him, Ichijo is ordered by his grandfather to spy on Kaname while attending Cross Academy; he refuses out of loyalty for his friend and attempts to break away of his grandfather's intentions. When Senri Shiki is possessed by Rido Kuran, Ichijo is forced to go against Kaname in order to protect his friends. Once Shiki is freed from Rido's possession, Ichijo rejoins Kaname's side and stops Kaname from killing his grandfather, instead asking that he be the one to handle the issue. It is strongly hinted at that Takuma intended to end his life along with his grandfather, saying "Together, let us put an end to the Ichijo line." But it is revealed that he never got his wish, as he was discovered unconscious afterwards by Sara Shirabuki, one of the only known Pureblood vampires, who said that she always wanted "to have" Takuma, as though he were simply a doll or a toy. He is currently in the hands of Sara Shirabuki, whose agenda is not yet known.

Hanabusa Aido (藍堂 英, Aidō Hanabusa?), nicknamed "Idol" by the Day Class girls, is known among the Night Class along with his cousin Akatsuki Kain to be "Kaname-sama's right hand". His fierce admiration for Kaname borders on zealousness and though extremely loyal to him, Aido has a tendency to overstep his boundaries, which results in Kaname punishing him if discovered. A noble-class vampire who can conjure and control ice, Aido often appears cheerful and friendly one moment, but vindicitive and cruel the next. A perceptive individual, he figures out Zero is a vampire, but he keeps this information to himself without any hidden agenda in mind.

Aido is not overly fond of Yuuki and dislikes the attention that Kaname gives her. He is temporarily troubled when he witnesses Kaname's killing of a fellow pureblood and runs away from the Moon Dormitory and imposes himself on Yuuki and Zero. Agreeing with Yuuki's assertion that he would remain loyal to Kaname even if betrayed by Kaname, he returns to the vampire's side. Aido has difficulty adjusting himself to referring to Yuuki in a formal manner following the revelation of her true nature when he is appointed as one of her protectors.

During Rido's attack on Cross Academy, Aido protects the Day Class, as ordered by Yuuki.

Akatsuki Kain (架院 暁, Kain Akatsuki?) is Aido's cousin and considered one of "Kaname-sama's right hands". While the Day Class girls have nicknamed him "Wild", Kain is actually mellower than Aido and his layback attitude and association with Aido frequently sees him getting into trouble, despite not being directly responsible.[6] He refers to Kaname as their "gang leader".[7].

Kain is incredibly perceptive and frequently sensitive to others' feelings, most particularly with Aido and Ruka's. While he initially suspects that Zero has killed Shizuka, he instantly realizes that was not what had transpired. Kain's ability as a vampire is the opposite of Aido's, the ability to conjure and control fire. Kain seems to have feelings for Ruka, often appearing at her side when she is feeling down about Kaname's unwillingness to accept her feelings.

During Rido's attack on Cross Academy, Kain and Ruka fight vampires attacking the Day Class.

Ruka Souen (早園 瑠佳, Sōen Ruka?) is a female vampire popular with the Day Class students and one of those who are the most faithful and protective of Kaname. She is a childhood friend to Kaname, Ichijo, Aido, and Kain.

Ruka appears to dislike Yukki because Kaname loves her while Ruka's own strong feelings for him remain unreciprocated. It was expressed in a flashback that even before she met Kaname, she had always had feelings for him to the extent of wanting to give him her blood. However, the only time he ever drank her blood was to protect Yuuki from his urge to bite her, and he has since politely refused to drink it. Ruka is upset when Kaname chooses Yuuki to be his lover, but finally accepts her when she discovers that Yuuki is Kaname's pureblood sister, even having Aido give Yuuki a pair of shoes to wear. Recognizing the foolishness of her obsessive feelings for Kaname, Ruka shows that while she remains as dedicated as ever to him, she is able to do so calmly and with a mature level-headed attitude.

During Rido's attack on Cross Academy, Ruka works with Kain to defend girls in the Day Class.

Senri Shiki (千里 支葵, Shiki Senri?) is one of the youngest Night Class members and works as a model with Rima Touya. When the Night Class is given orders to hunt down a level E vampire, Shiki is usually the one seen out hunting the level E vampires. He is able to control and bend his blood at will.

Senri also cares for Rima and they seem to have quite a relationship. In one of the episodes he was at the Vampire ball and one vampire said that he was too skinny, when the conversation finished he turned around quite shocked to see that Rima was offering to feed him.

Shiki's father is Rido Kuran, making him Kaname and Yukki's cousin, and his mother's uncle is part of the council. His mother was also a former actress, making the Shiki family well known. As part of a plan to resurrect himself, Rido possesses his son's body, though for Shiki to reassert himself is easier than he lets on. During Rido's fight against Rima, Shiki is able to awaken within himself and attempt to regain control of his body.

After Rido's revival, Shiki regained consciousness and after recalling the events that had taken place, apologizes to an unconscious Rima for letting Rido use his body and embraces her. He protects Rima from a servant of Rido and, as she regains consciousness, carries Rima away from the Moon Dormitory before it collapses. As Shiki escapes, he sees his father one last time before Rido's death.

Rima Touya (遠矢 莉磨, Tōya Rima?) is one of the youngest Night Class students and she works as a model alongside Senri Shiki. Her exact relationship with Shiki is unknown, though they are almost always seen together. She cares deeply for Shiki and possesses a personality similar to his. As a vampire, Rima possesses lightning or electricity related abilities[8].

After suspecting Shiki has changed upon his return to school, she confronts Rido and tells him to leave Shiki's body since she can tell that he is not Shiki. She is wounded by Rido, but is saved by Ichijo. While injured, she tries to convince Shiki to snap out of his state and calls him an idiot for letting Rido control him. Badly wounded, she is sent back to the Moon Dormitory by Ichijo. Protected by Shiki, she later awakens and they are forced to leave because of the building's collapse.

Seiren (星煉, Seiren?) is a student of the Night Class, she is Kaname's unofficial bodyguard. She is usually the first to defend Kaname from anyone she regards as a threat. She barely refrains from killing Zero when he threatens Kaname with the Bloody Rose. Seiren also appears to serve Kaname in the capacity of a spy or informant.

Headmaster Kaien Cross (黒主 灰閻理事長, Kurosu Kaien Rijichō?) is Yuuki's adoptive father, who also took Zero into his home for several years. Headmaster Cross dreams of peace between humans and vampires, and established the Night Class to promote understanding between the two races. Cross is shown to have a habit of provoking Zero and is eccentric in some ways, but he has a serious side as well.

The headmaster is revealed to have several secrets, including that he was a former vampire hunter. He knew both of Kaname's parents, who founded the Cross Academy peace treaty before their deaths, and feels indebted to them, in particular Juri Kuran, who had spared his life sixteen years ago after he had attempted to take away her life, not knowing then that she was pregnant with Yuuki. So, Cross has always known that Yuuki was a pureblood vampire, but chose not to reveal it. It appears as though Cross and Juri Kuran once had a relationship similar to Yuuki and Zero's[9], but in the end Juri chose Haruka. Even though Cross didn't end up with the woman he loved, he vowed to protect her two children, Yuuki and Kaname [10].

During the defence of Cross Academy, Cross stands against the hunters from the Hunters Association, refusing to kill any vampires and intending only to protect the Night Class as they defend the Day Class, and asserts that he has no intention of allowing the hunters take Yuuki. [11] His vampire hunter weapon appears to be some sort of sword [12], which he uses to kill the President of the Hunters Association who had turned corrupt from drinking Rido Kuran's blood.

Ichiru Kiryu (錐生 壱縷, Kiryū Ichiru?) is Zero's younger twin brother. When they were younger, they were both taught by Toga Yagari to become vampire hunters. Ichiru, however did not seem to share Zero's natural ability and was often ill. Zero and Ichiru were very close as children, although later Ichiru claims to have hated Zero after overhearing that his parents preferred Zero over himself.

Because Shizuka recognized Ichiru felt the same pain she did, she chose not to kill him and makes him her devoted and loyal servant instead. She lets Ichiru drink her blood to strengthen him and cure his chronic ill health, although she does not turn him into a vampire and he remains a human. With Shizuka's death, he attends Cross Academy as a Day Class student by the orders of Shiki's father, Rido Kuran, and Zero's permission. Ichiru's reasons for siding with Rido appear to involve Rido promising Ichiru that he will kill those who killed Shizuka Hio.

When Zero is arrested up by the Vampire Hunters Association, Ichiru visits him and appears to shoot him out of hatred. However, it is revealed that Ichiru was terribly wounded in an attempt to kill Rido, the one that Ichiru had actually been after because of his role in Shizuka's death. After he shoots his brother, Ichiru convinces Zero to actually eat his body whole so they can finally become one, as they were originally supposed to be. Ichiru states that he was happy that he was not dead in Zero's heart and when they hug, he says that he feels comfortable to be in his arms, recalling a time when the brothers slept in the same bed often and they were loved equally by their mother. After Ichiru's death, Zero appeared to grow vines, most likely from all of Shizuka Hio's blood that Ichiru has ingested [14].

Toga Yagari (夜刈 十牙, Yagari Tōga?) is currently the top ranked vampire hunter, as well as the one who trained Zero to be a vampire hunter. He lost his right eye trying to save Zero long ago. He appears at Cross Academy serving for a short while as a Night Class substitute teacher of Ethics, and to decide whether Zero is considered dangerous or not.

Yagari is shocked to learn the Council of Ancients' decision for punish Zero the death of Shizuka Hio and later appears to arrest Zero for other charges.[15] Before leaving Zero, he gives him the Bloody Rose.[16] Yagari subsequently joins the Chairman to protect Cross Academy from the Hunters Association.

Shizuka Hio (緋桜 閑, Hiō Shizuka?) is the pureblood vampire who bit Zero; even her fellow vampires are uneasy around her and refer to her as the "Madly Blooming Princess". A manservant whom she loved (a former human vampire, falsely classified by the Hunter's Association as Level E) was assigned to be killed by a Kiryu vampire hunter. Enraged and vengeful, she attacked the Kiryu family, killed Zero and Ichiru's parents, turned Zero into a vampire, and took Zero's twin, Ichiru, in as a devoted servant. She was originally Rido Kuran's fiancée, but they never married due to his disappearance and finally her death.

Because Shizuka's blood can prevent Zero from falling to Level E, Yuuki risks her life for Zero to be able to drink Shizuka's blood. However, to protect Yuuki, Kaname kills Shizuka and drinks her blood, leaving only a small amount for Zero to drink. Unfortunately the blood is drunk by Ichiru, who arrived to find Shizuka first. Before dying, Shizuka warns Kaname that he will live in darkness and has summoned a sinister future for himself.

Maria Kurenai (紅 まり亜, Kurenai Maria?) is a very distant relative of Shizuka Hio. She allows Shizuka to possess her body in exchange for being allowed to drink Shizuka's blood, which would strengthen her sickly body. Due to Shizuka's untimely death, this promise is never fulfilled. She seems to be fond of Ichiru, hugging Zero when she mistakes him for Ichiru, and asks Yuuki to tell Zero that if he sees Ichiru, to tell him Maria wants to see him again. She returns to her family after Shizuka's death, and when she sends an owl out to search for Ichiru she witnesses Kaname's destruction of the Vampire Council, and proceeds to spread the news.

Asato Ichijou (一条 麻遠, Ichijō Asatō?) is Takuma's grandfather and a member of the Vampire Council. He wanted to become Kaname's guardian after the death of Kaname's parents, but Kaname did not accept. He allows Takuma to attend Cross Academy for the purpose of spying on Kaname. His age and demeanor brings fear to many vampires, though Aido and Ruka openly confront him when Asato implies his desire to drink Kaname's blood. Many people call him Ichiō-sama (First Elder).

Sara Shirabuki (白蕗 更, Shirabuki Sara?) is a beautiful pureblood vampire who first appears in a party held by the Aidou family, stating to Kaname that "We purebloods have to stick together". She is called on by vampire society to stop Kaname when it is assumed that he has gone mad after killing the Vampire Council, though in actuality he had done so in self-defence.[17] Sara stops Takuma Ichijou from killing his grandfather, and says to herself that he "will be useful in her plans against Kaname".

Rido Kuran (玖蘭 李土, Kuran Ridō?) is a pureblood vampire, Shizuka Hio's former fiancé, Senri Shiki's father, and elder brother to Haruka and Juri Kuran. He is the main antagonist of the story. According to Asato Ichijo, he is the true head of the Kuran family. Ten years ago, seeking to take the Kuran princess, Yuuki, Rido killed his brother, Haruka. Kaname attempted to kill Rido, but found he was unable to and a triumphant Rido revealed that as the one who resurrected Kaname, he is Kaname's master[18]. Instead Kaname reduced Rido to the state where he required another pureblood vampire's blood in order to revive fully.

Secretly aided by the Ancient Vampire Council and the Hunters' Association, Rido manipulates events from the shadows by transferring his soul to other bodies and taking control. Rido possesses eyes of two different colors (crimson and blue), and when his soul is transferred to a different body, that body has the same eyes. When Rido takes possession of Shiki's body, he goes to Cross Academy. After a brief confrontation with Kaname and later Rima, Kaname gives his blood to Rido's body in order to restore Rido to his original body.

Ichiru reveals that Rido is the one who added Shizuka's ex-human lover to the list of Level E vampires to be liquidated by the Hunter's Association and attempts to kill Rido as revenge for Shizuka, but instead is mortally wounded. Following his true body's revival, Rido's vampires sense his revival and begin to attack the school students in order to capture prey for Rido to feed on. Rido attempts to compel Aido to feed upon him, but is thwarted by his niece. Seeing Yuuki's resemblance to her mother, Rido changes his original desire from eating Yuuki (in order to gain power) to taking Yukki as his lover as a replacement for Juri[19], who he loved but never wanted him. Rido's life comes to an end when he is defeated by Yuuki and Zero.

Juri Kuran (玖蘭 樹里, Kuran Juri?) is Yuuki's mother and a pureblood vampire who resembles an older version of Yuuki. Juri was the wife of Haruka Kuran as well as his sister since it is common for pureblood vampires to marry their siblings. Ten years ago when Rido Kuran (her oldest sibling) appeared, she erased five years of Yuuki's memories at the cost of her own life because she wanted Yuuki to live a normal human life. Headmaster Kaien Cross states that he is indebted to her, and it is revealed that she spared him his life after he attempted to murder her when she was pregnant. [20] Her last wish was for Kaname to look after Yuuki.

Haruka Kuran (玖蘭 悠, Kuran Haruka?) is Yuuki's father and a pureblood vampire. He is the brother and husband of Juri Kuran. It was stated that Haruka had been alive for nearly 3000 years and has known Juri for almost as long. He revealed that the Vampire Council was trying to use the status of pure blooded vampires and their powerful blood to serve itself. Before his death, he hugged Kaname and said that as a loving father, he did not want his child to enter the fight. He was killed by his older brother, Rido Kuran, in his attempt to stop Rido from killing Yuuki ten years ago.