Years before the events of the games, Shiunsai received an order to assassinate a particular samurai. Together with several fellow ninja, he infiltrated the home of the samurai and killed him. As he and the other ninja were preparing to leave, the dead samurai's wife and servant discovered the ninja. The others quickly dispatched the wife and servant, but as they moved to silence the baby clutched in the dead wife's arms, Shiunsai stopped them from killing the baby boy. Taking pity on the boy, Shiunsai brought the baby home with him and raised it as if it were his own flesh and blood. Shiunsai was already raising Tatsumaru to become a ninja and he decided that the new baby would follow the same path. After the baby had grown into a young boy and started his training as a ninja, it became apparent that he was something of a weakling.