UQ Holder!(ユーキュー ホルダー?) is a manga series by Ken Akamatsu. Set in the same universe of his previous work Negima! Magister Negi Magi, but over 70 years later, it follows the adventures of a young boy who is transformed into a vampire and joins a secret society composed of immortal beings.
The series is set in the year 2086, ten years after magic is revealed to the world. Tōta Konoe is a young boy who always dreamed to leave his home village and find out what lies atop the huge tower in the capital, but his teacher and guardian Yukihime claims that it will only be possible once he defeats her, a feat that seems impossible for him. However, once Tōta is mortally wounded by an enemy coming after Yukihime's life, his teacher reveals herself as a vampire and saves his life by transforming him into one of her kind. Thus begins Tōta's adventures in the world of the immortal beings in a society where magic and technology are highly advanced to the point of being almost indistinguishable.
The main character and a 14 year old boy who was raised by Yukihime after his parents died. After being mortally wounded while protecting Yukihime, he is transformed by her into a vampire, becoming an immortal being. Always cheerful and optimistic, Tōta is similar in hair color and family name with Konoka Konoe, a character from Negima! and is implied to be a relative of hers, making him part of the Konoe family. His grandfather was Negi Springfield, a legendary magician and Negima!'s protagonist. Tōta later receives a sword that can have its weight increased or decreased thousands of timesfold according to the will of its user (actually a adjustable dial) that becomes his main weapon and it is revealed that just like Yukihime, his body possess the secret power of "Magia Erebea", allowing him to absorb magic into his own body, bonding it to his soul. This power is due to having been turned into a vampire by Yukihime, who created Magia Erebea. Tōta's personality strongly resembles his great-grandfather's, Nagi Springfield's personality.
A 700 year old immortal vampire and a main character from the Negima! series. After parting ways with her friends from the Mahora Academy, possibly because she outlived them, Evangeline adopted the alias "Yukihime" (lit. "Snow Princess") and founded the secret "UQ Holder" society for immortal beings. She usually appears as a tall and attractive woman instead of the usual child-like appearance seen in Negima! and becomes Tōta's foster parent after his birth parents' are killed in an incident, later transforming him into a vampire to save his life.
The member number 11 of UQ Holder. Originally an assassin initially sent to murder Yukihime; 14 year old Kurōmaru is defeated by Tōta who "convinces" him to become his friend and brother-in-arms. As he also displays traits of immortality, Kurōmaru accompanies Tōta to join UQ Holder. Despite claiming to be a boy, Kurōmaru displays a feminine appearance and behavior and is usually mistaken as a girl. This is because he comes from a tribe of demi-humans where children are born genderless but becomes male or female once they reach the age of 16. Kurōmaru claims he wants to become male and stay by Tōta's side as his brother-in-arms, but feels conflicted because of his growing romantic feelings for him. Kurōmaru is similar in appearance with Setsuna Sakurazaki from Negima!, who was also Konoka Konoe's best friend and just like her, is an adept of the Kyoto Shinmei-ryū sword style and other Eastern battle techniques.
The member number 4 of UQ Holder. She is very devoted to Yukihime after having been saved by her in the past and is jealous of Tōta's close relationship with her. Her immortality is said to come from divine origin, as all her wounds heal instantly instead of just regenerating fast like in most immortals and because of it she was branded as a witch and hunted when she was a small child centuries ago.
The member number 9 of UQ Holder. She is an extremely wealthy girl and the main financial sponsor of the organization. She has the power to rewind time, averting adverse events like her own death by returning to specific instants in time she marks with what she labels as "save points". She also has the power to bring other people to the rewinded time with her, having them remember the erased events as well.
Also returning from Negima, he was Negi Springfield's main rival and comrade. He is currently heralded as the number one wizard in the Solar System and the current leader of "Ala Alba", the brigade Negi founded with his students 80 years before. He opposes UQ Holder, claiming that Yukihime was responsible for Negi's disappearance. However, Fate claims that there is a way to save Negi, and the fate of the entire Solar System depends on it. To do so, he claims that he needs Tōta's cooperation, but he is instead the target of his hatred, after revealing that he was the responsible for the death of his parents.