mahou sensei negima!
A 2003-2012 manga series written and illustrated by Akamatsu Ken, with a 2005 anime adaptation by Xebec, a 2006 spinoff anime by Shaft (as "Negima!?"), a 2006 manga spinoff of "Negima!?" (as "Negima!? Neo") illustrated by Fujima Takuya, and a 2008-2011 OVA series by Shaft.
Ten-year-old Welsh mage Negi Springfield is sent to Japan as a teacher as his training to attain the title of "Magister Magi". He ends up at Class 2-A of Mahora Girls' Junior High School, a particularly rambunctious class. Even as he balances teaching and training (with help from some of his students, the first of which is fiery Kagurazaka Asuna), Negi also attempts to discover about what became of his father Nagi, himself a legendary Magister Magi.
It is succeeded continuity-wise by UQ Holder!.