Death is Certain, the Time is Uncertain (Mors certa, mora incerta) Mahô sensei Negima! : Season 1 Episode 25

With the help of Chao and Satomi's time machine, Negi transports himself and Chamo to 1993 Germany to know more about Asuna's magic cancelling power and discover ways to bring her back in the present. In the process, he unknowingly takes along the rest of 2-A.