Unfortunately, Kamakiri and his two friends were evil and greedy for power. They plotted against Yukimasa, killed his loyal comrades and ambushed him. The whole pack seemingly turned against him.
Yukimasa begged them to spare his son and told him to escape. But Hiro attacked Kamakiri despite his orders and lost his right eye.
After this, Kamakiri turned his attention on Yukimasa again and didn't notice how Yukimasa's minion tetsu escaped with Hiro.
Then, Yukimasa was bitten to death by Kamakiri, Hiro would always remember his dying screams.