Who is Stephen Chan from The Samurai's Garden and what is their importance?

The book is Stephen's journal. Stephen is a young Chinese man, attending college and working on a life of his own, when he is diagnosed with tuberculosis. World War II is already in the making when Stephen is sent to live at his family's summer home on the beach in Tarumi, Japan. It's there that Stephen learns about himself, finds new friends, and contemplates his future. Before the trip, Stephen is extremely ill.