The Shadow Hero by Gene Luen Yang and Sonny Liew
In 1944 a hero appeared in rural China to aid the people in their fight against the invading Imperial Japanese Army. He was a man of mystery, his face always obscured, his shadow taking the appearance of a giant smiling turtle, and his origins known only to himself.
Here at last is his story. Herein lies the origin of that shadow hero, the Green Turtle.