Once was a normal guy, he is now an android with a motorcycle instead of his original lower body parts. He is the first subject the Heart Momentum was tested on.
In his last life, he was cool minded, but now, the reverse.
As said, he was once a normal guy, with a family and possibly could get a career, but one single road accident cost him his life. His parents were offered help reviving their son with the heart momentum, and they agreed, not knowing what the result would be. He was riding a motorcycle during that accident, and his legs were cut off of his body. The solution was, to replace the legs with something else, but building mechanical legs would give the corpse more than enough time to rot and they had to do something quick, so they connected an entire motorcycle to his lower part of the body as legs, and inserted the Heart Momentum. He indeed came back to life, but all of his memories of his family and his last life were now gone, and when he woke up, the scientists discovered that his personality has changed, learned from his reaction to the motorcycle connected into him. He just ran away from the hospital, not knowing how to operate the motorcycle legs.