Mahou Sensei Negima!

Following his graduation ceremony, 10-year-old Negi Springfield is sent to a Japanese school as an English teacher. To his surprise, he is assigned to an all-girl class. In addition to teaching (and being teased by) 31 cute girls while trying to keep his magic capability secret, he's also looking for clues about his father, who was once known as the "Thousand Master" but mysteriously disappeared years ago.
(Source: ANN)