The special quality granite found in Kitagishima, one of Kasaokaﾕs Islands, is easy to process and durable against water and fire. It is known nationwide as Kitagi Stone. During the period of the construction of Osaka Castle a great amount of Ishigaki stone was sent from the Kasaoka Islands. The stone is also used for a gigantic torii gate at the Yasukuni Shrine in Tokyo. Today, it draws the attention of sculptors for its use as a material for sculptures.

According to the abolition of clans and the establishment of prefectures in 1871, Fukazu Prefecture changed its name to Oda Prefecture in 1872 and the Prefectural office was placed in Kasaoka.
Although Oda Prefecture was the second largest in the Chugoku region, it was abolished in only three years. The eleven villages in Bitchu were merged into Okayama Prefecture and the six villages in Bingo were merged into Hiroshima Prefecture. The present Kasaoka Elementary School tract is the site of the old Oda Prefectural office. Only part of the moat and the front gate remain and they are appointed to the cultural assets of city.

This is an old bon dance handed down on Shiraishijima Island of the Kasaoka Islands. It was originally started to mourn for the warriors killed in the Genpei battle in this sea area. The biggest characteristic of Shiraishi Dance is that of including a lively "man dance" with a sedge hat, kimono and haori half coat, and a little moderate "woman dance". 13 kinds of various dances are performed together in one circle with one leading chorus and the accompaniment of a big drum. It is designated as an important intangible ethnic cultural asset and it is known both nationally and internationally.

The area around Konoshima Waterway is designated as the only breeding grounds for the horseshoe crab, a natural monument of Japan. A horseshoe crab is called a living fossilﾓ, which separated from the trilobite in ancient times and has not changed its structure in 20 billion years.
Following the slogan of Sewage to preserve the horseshoe crabﾓ, conservation of the dry beach for habitation and egg laying by the horseshoe crab is enforced through maintenance of sewage, improvement of water quality and a system of sand dikes in the breeding area.