Shizuo is the second son of three to a family of hunters and trappers living up a snow-capped mountain. His father taught the brothers by leaving them out in the night with little more than basic trapping tools, expecting them to learn through harsh experience. It was then, at 14 years of age, that Shizuo recieved the scars down his cheeks as a buck charged and tried to gore him. Managing to survive the night, he was subjected to more tests and lessons in brutally taking down the animals of the mountain.

Both of Shizuo's brothers were far more successful than he and took a particular shine to the family's brutal methods, so he left to travel in search of someone who could guide him another, more peaceful way through life, holding onto a strand of hope that the world was not this savage. He was able to find a teacher of the blade and discovered a proficiency for the naginata. This teacher gave all he knew to Shizuo - knowledge of demons and the Ice Breathing technique as well as more humane hunting methods to properly take care of himself out on the road.

He was able to master the techniques and pass the final test at 19 years old, staying mentally strong with the knowledge that his techniques allow the demons to pass on without pain despite the lives they have cruelly taken. After traveling for over 3 years and finding that humans can often be as evil as demons, Shizuo made his way to the temple in the hope that the world isn't as dark as it seems and he can find people who will fight with him against all evil, human or demon.