Green luminescent mushrooms nicknamed "forest fairies" on a western Japan mountain offer visitors a touch of fantasy, with this year's observation tours starting Saturday.

The species of fungi called Mycena lux-coeli with a cap measuring 1 to 2 centimeters in diameter glows in rainy conditions due to the work of an enzyme that oxidizes luciferin, a light-emitting compound. It can only be found in Japan.

The mushroom was first discovered on Hachijo Island in the Pacific in 1951 and on Mt. Mesame on Ugui Peninsula in Wakayama Prefecture in 2001. Currently, it can also be found in Mie, Hyogo, Oita and Miyazaki prefectures.

A local group will host the tours every weekend from Saturday to July 14 as well as Sep. 1 to 29. The admission fee is 500 yen ($4.50) per adult and reservations should be made at least two days in advance.

The mountain is off-limits except for the mushroom observation tours due to environmental conservation.

"The glowing mushrooms are usually seen in rainy conditions in the summer and fall. I'd like visitors to experience the dreamy world," said Shigeru Nishigaito, a 79-year-old tour guide.