Shinji grew up in Japan, and had a generally unfantastic childhood, always known as a clown and a chatterbox. He graduated and moved to go to college for the arts. A year after, he was caught in an accident in a cross section, and was injured in a way that he lost his voice. (It is possible. Being hit on the head can damage the Broca's Area)
This brought on a burst of depression, and drove him to further indulge in alcohol and spend more time in bars. After a little while, he bought an ocarina on a whim, and found it to be very therapeutic, almost as though he had his voice back. He started performing at some of the bars he frequented.
