During the #YouaskYu twitter session we learned that the plaster on ryo face was due to an injury in a martial arts Tournament which leads me to speculate that the story of shenmue and ryo did not begin with him just simply coming home one day to find something wrong.
Rather there may have been a little chapter with him at a martial arts tournament in which he has a tough competition where he is hurt but eventually wins. maybe it was a school tournament at suka high. And after winning in the tournament and making the hazuki style proud he is eager to to get home swiftly so he can tell his dad about his victory and make his dad happy and proud of him. So he runs home...
And that's where the shenmue 1 we know begins....