Yashima is a peninsula situated to the east of Takamatsu City in Kagawa Prefecture. It is a lava plateau that is a kind of the mesa. Yashima ,about 290 m high, 3 km wide, protrudes out into the Seto Inland Sea. Yashima has a flat top that looks like a roof. It is famous as the site of a battleground where a general from the Genji clan Minamoto-no-Yoshitsune defeated the Heike. Visitors can be overlooking the archipelago of the Inland Sea from the hilltop.