Mizushima (水島) is a small uninhabited coastal limestone island at the mouth of the Kuma River at the northern end of the Yatsushiro Sea in Yatsushiro, Kumamoto Prefecture, Japan. An episode in the Nihon Shoki explains how the isle gained its name: on the eleventh day of the fourth month of the eighteenth year of the reign of Emperor Keikō (AD 88), the Emperor, near the end of his tour of inspection of Tsukushi, laid anchor at the island and partook of food. When he then asked Ohidari (小左) for water to drink, he was at a loss, there being no ready source to hand; praying to the gods, a spring issued forth, which he drew and proffered to the Heavenly Sovereign; from this the isle takes its name of "water island". The island also features in two poems by (長田王) in the Man'yōshū (III.245 f.).