Our reporter visits 3 peculiar caves. In Yamaguchi Pref., he goes into Japan's largest limestone cave network at Akiyoshi and ventures into a cavern, accessible only by sea on Omi Island, with blue waters comparable to the grotto on Italy's Capri. In Shimane Pref., he explores the Iwami Ginzan Silver Mine, a UNESCO site that once provided a third of the world's silver. Also, our correspondent shows us the secret in the fascinating beauty of nishikigoi, a variety of carp known as "swimming jewels".