Hiro was born to an unremarkable family into a unremarkable life. With Japan's rigid social structure, he had nowhere to go. So he decided to make his own way. His older brother could take care of their family and that let Hiro explore on his own. He was a handyman and worked odd jobs, but the money really started to pour in when he worked for a couple yakuza members. He was good enough at fixing up appliances and cars to get a few more jobs with them.
And a few more. Hiro couldn't say no to easy money, so he fell in line fixing up their rides and joining the gang. It was a surprisingly predictable life and he was settling into it. He had friends and a place he could go home to.
Too bad it all went to s**t when Hiro lost his money by investing in a friend's business. He was ready to jump off a bridge to make sure no one would try to take it out on his family- until a young woman stepped in and stopped him from jumping. She convinced him to stay alive and keep fighting. Now he owes her and he's set on paying her back, no matter the cost.