Demon General

The Demon General (魔将軍 Ma Shōgun) is the final antagonist of Mahou Sensei Negima! 1st anime. He is the one who gave Asuna Kagurazaka the magic cancel ability and caused her death in her 14th birthday.

He doesn't appears in both manga and 2006 anime adaptation series.

Mahō Sensei Negima! (1st Anime)
The Demon General was summoned by Asuna when she was 4 years old, and made a contract with him to lose or at least suppress a natural magical ability she possessed: the power to summon demons. The Demon General told Asuna the price of the contract was that she will die at 12:00 midnight on her 14th birthday (That date would be 23 October 2003), and Asuna agreed.

After Nagi Springfield’s disappearance, the Demon General absorbed young Asuna and planned to use her as a barrier. After some convincing by Negi Springfield and his students, young Asuna assists them in destroying the Demon General. However, even with the Demon General’s demise, the contract could not be terminated.

After returning to the present day, to the time where the class was celebrating Asuna’s birthday, Chao Lingshen, Satomi Hakase and Evangeline A.K. McDowell invented a special device that, working right under the World Tree, combined with all the special powers of Negi’s students, successfully terminated the contract for good.