The "Chibi Vampire" manga series and its light novel adaptation feature a cast of characters created by Yuna Kagesaki. The series takes place in a fictional Japan where vampires live amongst humans and are slowly dying out from lack of reproduction. Among them is Karin Maaka, an unusual vampire who does not drink blood but instead must inject it into others because her body produces too much. The youngest child in a family of vampires, Karin lives like a normal human teenager, attending school and walking in the daylight with no harm to herself. Her parents, Henry and Calera Maaka, along with her older brother Ren and younger sister Anju, worry about her unusual nature. At school Karin meets a new transfer student, the human Kenta Usui, with whom she becomes friends and later falls in love. After he learns her secret, he agrees to help Karin during the day when her vampire family is unable to watch over her. While the awkward couple deal with the issues of a relationship between a human and a vampire, they meet Yuriya Tachibana, a human-vampire hybrid sent by her uncle Glark to look for the "psyche" of vampires. The pair eventually kidnaps Karin, the "Spring of Psyche", and intending that all vampires drink her blood so that it may rejuvenate their species.
The anime television adaptation features character designs by Yumi Nakayama and a slightly modified story. Yuriya, Glark and Bridget do not appear; instead, the Maaka family finds itself targeted by the Sinclair family of vampire hunters. Victor Sinclair wishes to destroy the family, blaming them for his family's "shame" because his ancestor Alfred Sinclair fell in love with Elda Maaka, Karin's grandmother. Victor blames Elda for loving Alfred and filling his life with sadness. Victor's grandson Winner initially aids him in his quest, but develops feelings for Karin who gave him confidence when he questioned his ability to follow his dreams.
Protagonists.
Karin Maaka.
 is descended from a long line of purebred vampires. However, instead of having to drink blood like normal vampires, Karin's body overproduces blood. Generally, once a month she reaches a point where she can no longer hold it in, and she must bite someone to inject them with her blood or else suffer from a massive nosebleed. In the anime, if Karin goes too long without biting someone and tries to hold her blood in, she enters a "berserker"-like state and aggressively attacks the first target she can find. Being near a person suffering misfortune causes Karin's blood to increase ahead of schedule. Due to her unusual situation, Karin lives like a normal human rather than a vampiress. She lives in the daylight, is not susceptible to common vampire weaknesses. and lacks the skills normal vampires have. These differences cause her to be somewhat separate from her parents and older brother, whom she only sees for a few hours in the time before she goes to sleep (she spends more time with her younger sister Anju, who has not yet awakened as a vampiress). In the first chapter Karin meets Kenta Usui and is dismayed that her blood increases around him. He has a lot of misfortune in his life. Karin resolves to do favors for him and thus reduce his misfortune and her blood problems around him. As the series progresses, Karin falls in love with Kenta. He returns her feelings, though Karin is initially troubled to learn that human-vampire children are born sterile.
Karin is rendered unconscious for several days after trying to hold in her blood and suffering a massive nosebleed, during which time her family grows increasingly concerned that her condition would kill her. Her mother journeys to her birthplace in search of answers and learns that Karin is a rare vampiress, called the "Spring of Psyche", that is born when the vampire species is struggling. The blood Karin produces can bestow fertility in other vampires. Karin is later kidnapped by vampires who want to feed from her to rejuvenate their own lives, though it will kill Karin in the process. They also plan to impregnate Karin against her will to continue the Psyche's existence. After Kenta and the Marker family save Karin from the Brownlicks, her nose-bleeding ceases, leaving her as though she were a normal human, who will likely grow old and die. Her family erases all of her memories of vampires, including themselves, promising Kenta that they will continue watching over her happiness although she will not know them. At the end of the series, Karin and Kenta have married and are shown to have a teenage daughter named Kanon.
In the anime adaptation, the blood-making issue and Karin's capture are not mentioned. Instead, Karin has the opportunity to become a full vampiress, which she initially declines, but then pursues after Kenta encourages her. The transformation is interrupted and Karin goes berserk. Kenta comes to her rescue by volunteering to be bitten, ending the berserker rage, confirming their romantic relationship. at the end of the anime she is still not a full vampiress and is still dealing with her blood-making issue, still has of all her memories and still lives with her family and spends much time with Kenta. In the anime television series, Karin Maaka is voiced by Sayuri Yahagi in Japanese and Chelsea Curto in English.
Kenta Usui.
 is the first human to have found out Karin's secret. At Anju's suggestion, the Marker family makes him an ally to aid in caring for Karin during the daylight hours. Kenta and his mother live in a one-room apartment and do not have much money. Consequently, Kenta cannot afford three meals a day, often leaving him hungry during the middle of the day. Karin, realizing this, begins making him a bento box lunch every day. Kenta works with Karin part-time at Julian Restaurant, seeking all the extra hours he can to support himself and his mother. He dreams of being a model citizen with a family and a good job. As a child, he was ignored by his maternal grandmother due to the circumstances of his birth. This leads to his being a person who tries to live a life free of prejudice and allows him to sympathize with Karin's unusual nature. He offers his neck to Karin to bite whenever she needs so she won't have any more nosebleeds. Karin ends up biting him twice, with the second bite following their first kiss. (It was thanks to Maki and Sophia's encouragement th a Kenta opened his heart to love.) When Karin is kidnapped, Usui aids the Markers in tracking her down, led by Sophia Pistis, the spirit of the first Psyche. While they are there in Kenta's hometown and at Karin's suggestion, Kenta goes to see his sick grandmother, not wanting to lose the last chance to reconcile with her. After Karin's memories are modified by her family, Kenta, whose memories weren't erased, promises to keep her heritage a secret and to make her happy. At the end of the series, they are married with a child, the reincarnated spirit of Sophia. In the anime television series, Kenta Usui is voiced by Katsuyuki Konishi in Japanese and Yahav Rom in English. He also appears to work very hard for his family and their daughter apparently has a crush on Ren. Something that Kenta's oblivious about and annoys Karin. While being around Usui some bluntly point out that the way his eyes are creepy, which makes Usui feel annoyed or down.
Antagonists.
Yuriya Tachibana.
 is a half-vampire who first appears in the eighth volume of the series. She moves into Karin's town at the behest of her uncle Glark to seek out an unusual vampire. Because she is half-vampire, she can also walk in the sunshine and only has to feed once a month, however she is sterile and will never be able to have children. When Karin befriends her, Yuriya initially lies to her uncle and tries to protect her. She is nearly killed by Elda Marker after she is discovered. She later betrays Karin, reluctantly helping her uncle because her uncle means more to her than Karin does. They capture Karin so that she can be used as the Spring of Psyche. Yuriya, as a half-vampire, was mistrusted by full-fledged vampires because it was the half-vampires who had betrayed them in Europe and led the vampire hunting church against them two generations ago.
Later, Yuriya expresses remorse for her part in Karin's capture and helps her escape after seeing a vision of her mother, a by-product of coming into contact with Karin's blood months beforehand. After Karin is safe, Yuriya goes to find her uncle to ensure he finds safe shelter as the sun rises. Near the end of the series, Yuriya is living with her uncle again. She returns briefly to Karin's town, but only shows herself to Kenta out of concern that the hovering Markers would kill her if she tried to approach Karin directly. She asks Kenta to pass Karin a new cellphone to replace the one broken during Karin's kidnapping, before saying her goodbyes, noting that she will probably not see either of them again.
Bridget Brownlick.
 is a powerful and ambitious vampire, of a powerful and ambitious vampire clan. When Glark offers her the Spring of Psyche, a vampire that produces blood which, if consumed by vampires, will increase fertility, she leaps at the chance. Her family has controlled the Psyche for many generations until James Marker convinced Cecilia Armash, whose family produces the Psyche every thousand years, to allow her daughter Calera to marry into the Marker family. After Karin is rescued, Ren detains Bridget so that Kenta and Karin may get away. Months after Karin's rescue, Bridget calls to let Ren know she is pregnant with his child, the first vampire child conceived since Anju Maaka. It's revealed by Karin, that Bridget gave birth to a son named Rei. Bridget also believes that her intimate time with Ren and her pregnancy means something more, as she had left Gilbert. And stated she wants him to be married to her, so they can raise their child. However, whether not wanting the responsibility of fatherhood or the shock, Ren wants nothing to do with her. And years later, its shown he's never had contact with them. Only years later does he reveal himself to his son, though only to protect Karin's daughter. Bridget thinks he's come to reunite and become lovers again, though he clearly is horrified at the idea of being with her.
Glark.
, when he first enters the story, is an Osaka-based criminal, seen punishing two under-criminals for botching an assignment. He believed that conditions are ripe in the vampire community for the rebirth of the psyche. He aimed to identify her and then profit from that knowledge. He sent his niece Yuriya to Shiihaba City to check out the Markers and report any unusual vampires she saw. Since he hadn't given Yuriya a complete briefing or gotten her full buy-in, it took a while for Karin's name to get back to him. He then contacted the highest vampire clan, the Brownlicks, and Bridget Brownlick came to take Karin. He knew that the vampires, in their greed, would drain Karin of her blood to restore their fertility, so he sought to get first in line, as well as taking the forethought to have her forcefully impregnated to ensure the creation of another Psyche. This is thwarted by the Marker family who rescued Karin and prevented anything happening to her. After a fierce battle with Henry Marker, (with assistance from Elda Marker) Glark is left behind to die in the sunlight but is luckily saved from being caught in the sun by Yuriya. Afterward, he contacts Henry to see if they can find a way to use Karin's blood without harming her, but is informed that she is no longer producing excess blood.
Victor Sinclair.
, a character created for the anime adaptation, is Winner's grandfather. Disgusted by his ancestor's seduction, which he blames for his family's exile from society, he holds a strong grudge against all vampires, particularly the Markers. An expert hunter and skilled fighter, his goal is to rid the world of the Markers and erase his family's shame. Though he recognizes that Winner only achieves his goal of