The School Excursion! Run, Kunoichi!

Urusei Yatsura – Season 0

First episode with Kaede, the ninja girl. On a school trip to a rustic village, Ataru finds a scroll dropped by a female ninja, Kaede. Her ninja master has her try to get it back by pretending to have a fondness for Ataru. But Lum shows up to protect her darling. So the master gets two more female ninjas and a clan of baby ninja's.