A country's special natural monument, the largest domestic limestone cave in Aki-dong, the fantastic sight of milky white stalactite spreads, and many tourists visit.

According to Misaki-shi, it is confirmed everywhere that a part of the stalactite has been discolored to green this time.

For this reason, the city decided to set up a committee by experts and decided to investigate the cause as it was necessary to protect the original cabbage.

According to the city it is considered that the stalactite is discolored due to breeding of algae and the like.

In Akiyoshi-dong, lighting that illuminates the inside of a cave seven years ago was replaced by a fluorescent light to an LED for energy saving measures, and according to experts the wavelength of light affected breeding of algae and the like It is also possible.

Kenji Shinoda, Director of Miyako City Cultural Property Protection Division, said, "Since Akihodo is a property of the people, I would like to investigate politely and take measures."