Nagi, the top graduate of a certain magic school in the UK, is currently just a 10-year-old boy. His goal is to become an "excellent magician." The graduation project assigned to Nagi by the magic school is "to be a teacher at a regular school in Japan"! With the help of his grandfather's friend, Nagi enters Mahoroba Academy and becomes the teacher of the secondary department's 2nd-year A group, which consists of 31 girls.
According to the legends of the magicians' world, there is always a brave warrior protecting a magician. These partners who assist magicians are called "magician's servants." Since Nagi is still a child, he has not yet entered into such a contract. However, after entering Mahoroba Academy, Nagi unexpectedly forms a contract through a KISS with a girl named Asuna Kagurazaka. From now on, it seems that a series of amusing and chaotic events are about to begin...