Nemuri Kyôshirô 6: Masho-ken

When the lord of clan has a son, the son will take his father's place. However, as the child gets older, the clan lord realizes that he is not the father of the child, and decides to have him murdered. Saved by a servant, the son is put into hiding and believed to be dead. So when his father dies, the son decides to claim what is rightfully his, namely, the leadership of the clan. The clan, however, has different ideas, so the young man decides to let his sword reason with his would be usurpers.