Negima!

Negi Springfield takes on the roles of English and homeroom teacher for Mahora Academy Class 2A while searching for information regarding his missing father Nagi (later 3A). Most of Negi's new classmates, including his roommates Asuna Kagurazaka and Konoka Konoe, become familiar to him rather quickly. Negi's student Evangeline A.K. McDowell, an immortal vampire and one of his father's adversaries, presents him with his first significant test. Asuna performs a "Pactio," a kind of magical contract sealed with a kiss, to consent to join Negi as his temporary partner in order to assist him in confronting Eva. After dealing with Evangeline, Negi leads the class on a trip to Kyoto in an effort to learn more about his father's whereabouts. However, he is forced to engage in combat with Eastern mages who are trying to kidnap Konoka, and enlists the aid of other students—including Nodoka Miyazaki, Setsuna Sakurazaki, Konoka's childhood friend—as well as Konoka herself—to save her. Another magician who appears to be around Negi's age but shows to be much stronger than him is introduced in the arc by the name of Fate Averruncus. After the events in Kyoto, Negi realized his own weakness. He started training with a number of pupils to grow stronger, and Kotaro Inugami, one of the enemies he faced there, unexpectedly made a comeback and formed a family with Negi's students Natsumi and Chizuru. Along with Negi, Kotaro fights Wilheim, a historical villain who, like Fate Averruncus, appears to be a tool of an even more formidable foe.