Negi's father and a legendary wizard. The origin of his title is ambiguous; some bill him as the master of a thousand spells (which is patently untrue since he admits to being a dropout who only knows a handful of spells, and needs to read out of pocket notes to cast other spells). However, this was stated in a dream that Evangeline had, and because she "hates" him, may not be true. However, it seems to have been verified by Asuna having Nagi say something to the same effect during her most detailed flashback dream. There is also a rumor that he made probationary contracts with a thousand different girls, though this is almost certainly just a lie of Albert Chamomile's, meant to inspire Negi to make many contracts and earn Chamo-kun a huge brokerage fee with the Ermine Society. However, the fact that Nagi's Probationary Contract with Albireo Imma (see below) bears the number 1001 (as the Roman MI) could support this rumor. Nagi is so strong, in both magical and physical combat, that he does not even need any Ministra Magi to help him. His fighting style was that of a magic swordsman, using both speedy magic casting and hand-to-hand combat in tandem.

Despite what many people thought, he never did graduate from a wizard school, because he was a dropout. When he was ten years old, he became the winner of essentially the last Legendary Mahora Martial Arts Tournament, twenty-five years before the current one. Later, Nagi and his friends fought in a magic war that ended when he was fifteen years of age. After the war, he became famous for his heroic deeds and received the title of Thousand Master. He disappeared ten years ago in 1993, the same year Negi was born. No one knows precisely what happened to him, but most people assume he is in fact dead (In a recording made by Alberio shortly before Negi's birth, Nagi himself assumed that he would be dead by the time Negi saw it). However, Nagi at least managed to survive until four years later, where he showed up just in time to save Negi from a horde of demons attacking his home village. He seemed to still be in trouble however, as he could only stay long enough to give Negi his staff. According to some flashbacks, Nagi is a nice and playful man, with a cunning and shrewdness that surpasses common sense. The illusionary Nagi created by Alberio was much the same, though with a noticeable ego. It has been speculated that since Alberio has a pactio with Nagi, which is still currently active, this proves that the Thousand Master is still alive.