Iga-no Kabamaru

For most of his life, Iga Kagemaru has lived in the mountains with his grandfather, the tough martial arts teacher Seizo Kagemaru. When his grandfather unexpectedly passes away, he is taken in by Seizo's first love, Ran Ookobo, who runs a school in Tokyo. Iga arrives in Tokyo and must deal with living in a town and attending a school for the first time, and all the trials and tribulations it brings - bullies, rivalries, romances and having to deal with an old friend (imdb)