Negima! Magister Negi Magi Vol 15

Negima! Magister Negi Magi Vol 15 by Ken Akamatsu. A Fantasy manga rated Older Teen, published in English by Kodansha in 2007.

Ten-year-old Negi Springfield is a genius wizard-in-training, and his final assignment before graduating is to work as an English teacher at an all-girls middle school in Japan. Keeping his magic secret from a class of thirty-one rowdy students turns out to be harder than any spell.