Lone Wolf and Cub: Baby Cart in Peril (1972)
Lone Wolf and Cub: Baby Cart in Peril (Japanese: 子連れ狼 親の心子の心 or Kozure Ōkami: Oya no kokoro ko no kokoro, literally Wolf with Child in Tow: The Heart of a Parent, the Heart of a Child), is the fourth in a series of six Japanese martial arts films based on the long-running Lone Wolf and Cub manga series about Ogami Ittō, a wandering assassin for hire who is accompanied by his young son, Daigoro.
More at Wikipedia.