With the arrival of Japan’s rainy season, a mysterious type of green, glow-in-the-dark mushroom begins to sprout in Wakayama prefecture. The Mycena lux-coeli mushrooms, known locally as shii no tomobishi-dake (literally, “chinquapin glow mushrooms”), sprout from fallen chinquapin trees. As they grow, a chemical reaction involving luciferin (a light-emitting pigment contained within the mushrooms) occurs, causing them to glow a ghostly green.