『Kuesu Jinguuji』

Kuesu is the heiress of the Jinguji Family(神宮寺家, Jingūji Ke, ranked#12), a Demon Slayer family that uses Western dark magic, who made her first appearance in chapter 15 of the manga. She is Yuto's fiancée, claiming that both of their families had promised their future marriage, and dresses in Gothic Lolita fashion. She is condescending towards ayakashi and, unlike Yuto, is fully trained in her Demon Slayer heritage. She is very arrogant and haughty as a result of her upbringing, and is shown to be highly aggressive and assertive, once kissing Yuto twice in front of Himari during her debut to stake her claim. She also has an enduring rivalry with Himari over Yuto, which stems from their first encounter in Noihara when she told Himari to stay away from him, and made Yuto allergic to cats with her magic so Himari couldn't get close to him. Prior to leaving for England to study magic, she and Yuto made a promise together to fight ayakashi, which was forgotten due to the magic in Yuto's amulet. Like the other girls, she, too has feelings for Yuto, but due to him befriending ayakashi, which to her is contradictory to his duties as a Demon Slayer, she often displays yandere traits. She slowly begins to accept the ayakashi siding with Yuto as her comrades, though this does not change her views about them should they betray him.

Kuesu is on unfriendly terms with the other Demon Slayer families, as her family was looked down upon by them and the ayakashi as heretics and outcasts for using Western magic. The only Demon Slayer family that didn't look down to them, however, was the Amakawa Family. Because they were one of the higher-ranking families, the Jinguji Family tried to make allies with them through marriage(even Himari speculates it as a well-thought idea). One of Kuesu's notable features is the crescent-shaped mark on her forehead, similar to the one that often appears on Sailor Moon's Usagi Tsukino. Because of this and her relentless killing of ayakashi, she is given the infamous title of Twilight Moon(黄昏の月, Tasogare no Tsuki). She also gained some infamous nicknames such as Crowley's Daughter(クロウリーの娘, Kurōrī no Musune), Second Marginal(セカンド・マージナル, Sekando Mājinaru), and The Smiling Cluster Bomb(微笑むクラスターボム, Hohoemu Kurasutā Bomu). Another notable feature is her silver hair: originally black, it changed color while she was studying abroad in England as a result of being exposed to and absorbing all the knowledge of a forbidden tome containing infinite knowledge(another student had pretended to befriend her in order to use her to gain the forbidden knowledge for herself and her sect; Kuesu gained the knowledge, but all of the sect members were either killed or lost their souls in the process). The reason the tome was forbidden is that everyone else who tried to acquire the knowledge it contained died from various reasons, such as their heads exploding.

As a descendant of the Jinguji Family, Kuesu can cast various magic spells through her spellbook, though she can easily cast these spells without it. During their fight, she told Himari after losing her spellbook(Himari had made a grave error in believing that the book was the source of her magic) that her spellbook didn't act as a talisman or focus to enable or enhance her spells, but was in fact a limiter to decrease her enormous power(so she would do less damage to the area such as making just a small crater where her target stood as opposed to wiping out most of the hill they were on). She also has the ability to teleport and wields a Stechkin APS machine pistol loaded with magic bullets as her personal sidearm. Similar to the Amakawa Family's power, the Jinguji Family's dark magic has only been passed down to female members of the family.