Sasuke left his início when itachi slaughtered the entire uchiha clan including his parents since then he was living alone then for greater power he abandoned leaf and went to Orochimaru........since then he is like a nomad roaming from place to place........
This whole animê movie is about homeless people finding a abandoned baby in the trash. It isn't a very 'pretty' animê but it sure does have a good message. They try to find the baby's parents and try to care for her even though they have nothing.