Tosa covers the entire southern coast of Shikoku and is a moderately wealthy province that offers a safe haven from the aggression of most other clans. It has plentiful woods, making it a good place for shipbuilding. Today, Tosa has the only castle in Japan that retains both its original keep and palace. Kochi was constructed by Yamauchi Kazutoyo, the provincial ruler, after the Tokugawa victory at the Battle of Sekigahara.