Who is The Boss from A Wild Sheep Chase and what is their importance?

The Boss is an unseen character in the novel, but is a primary force throughout the book. Born as a poor farmer in Hokkaido, he became a Pan-Asianist and was imprisoned for his beliefs as a youth. In 1945, doctors found a brain cyst and allowed the U.S. Military to test the man for a year. During these tests, the doctors supposedly worked with the Boss to discover spy activities in Japan in exchange for millions of dollars. During this time, the Boss also became a severe insomniac and often had hallucinations of sheep.