The central character is Saya Kisaragi, an ordinary school girl and a shrine maiden living near Lake Suwa,[1] who at night, hunts an ancient demonic race called the Elder Bairns.
[a] Her life changes drastically, as she finds out that she's been living a lie as she is an Elder Bairn in human form that was given false memories and actors that were staged to play the townspeople, her friends and family.
The café owner, Fumito Nanahara, is revealed to be the mastermind behind the experiment, releases the Elder Bairns and kills off the actors, and shoots Saya on the head.
The Tower is formed by Nanahara-clan and Mogari-clan, and both families controls the Shrovetide, a covenant which allows and gives the Elder Bairns to eat humans.
[2] SIRRUT is a covert group that appears in The Last Dark film, resisting Fumito Nanahara's new Youth Ordinace Bill, which enforces a curfew for minors and regulates the usage of the internet.
The main members consist Kuroto himself, Itsuki Tomofusa, Haruno Yanagi, Mana Hīragi, Shun Fujimura, Iori Matsuno, and Hiro Sukiyama.
During the events of Demonic Moonlight, she is then woken up by an American military officer named Lucy and started working for her.
[7][8] In the events of the 2011 anime series, Saya Kisaragi is living as a high school girl and a shrine maiden with a man named Tadayoshi as her father, and defends the town at night from the Elder Bairns.
Her battle with the Elder Bairns becomes difficult as they accuse her and the humans violating a covenant called "Shrovetide", and starts attacking during the day.
Near the end of the series, Kanoko, her teacher and her thought-to-be-fallen friends, forces her to drink the blood of the Elder Bairn.
[1][9][10] In the events of The Last Mind, an amnesic Saya is woken up in a shopping district near Tokyo, by an unlicensed doctor named Haru, who reveals to be her fiancée.
[11] In Asura Girl, in a pre-World War II-era, Saya is seen with Tadayoshi, who encounters a village conflict with Special Political Police force.
After Fumito revealing her killing Mana's dad during her arrival to Tokyo, Saya battles him, who transformed into a giant-Elder Bairn with Kuroto.
In Demonic Moonlight prequel manga, he recruits Kagekiri (and renames him Tadayoshi), and both capture Saya.
Fumito reveals that the town they're currently in near Tokyo was an experiment prior to Ukishima, and Haru and Ran were his test subjects.
Near the end, Fumito reveals Kuroto, his cousin that leads SIRRUT, was working with him, and turns him into an eyeball-Elder Bairn.
[8] In the events during the 2011 anime series, Tadayoshi is a father to Saya Kisaragi, acting as a head of the Shinto shrine, and supervises her role as a slayer of Elder Bairns.
Near the end of the series, they're revealed to be alive, and to be former criminals who participated in Fumito's experiment to have their records erased, so they could find work.
In the end of the series, she reveals that she's a scholar who agreed to participate on Fumito's experiment and learn about Saya and prove the Elder Bairns' existence.
Motivated by their heart-to-heart conversation, she helps Saya infiltrate Tower's main base by hacking.
He is Fumito Nanahara's grandfather, and the one responsible for giving Saya's false memories, as well as her curse of not being able to kill humans.
[8] In The Last Mind, appearing flashback, in his deathbed, he makes Saya promise to protect his grandson, Fumito, who believe has the source to her dependence on Elder Bairn blood.
Kutō (九頭) is Fumito's bodyguard that appears in Demonic Moonlight prequel manga and The Last Dark film.
In Demonic Moonlight, he is responsible for resurrecting Mahito Nanahara through the body of a child, and assisting his plan.
[8] In The Last Dark, he informs Fumito that the experiment escaped, and is seen ambushing and fighting Saya at Tsuji Private Academy.
[2] Dog (犬, Inu) is a character that converses with Saya during the course of the anime series, being the one responsible for granting her wish to remain herself.
[12][10] Its true identity is a familiar of Kimihiro Watanuki, a character from xxxHOLiC manga series (by CLAMP).
He later reappears in The Last Dark (both dog and human form), as he gives Saya a new sword, and notices a close bond with her and Mana Hīragi.
She was also responsible for suppressing Ren's seizures to prevent his awakening, and successfully turns Ran into an Elder Bairn.
The Elder Bairns (also known as the Old Ones) are a demonic race that silently preys on humans and eats their flesh, whose feedings are under control by an ancient agreement called "Shrovetide".