This fellow was down on the creek, hanging on the grass stalk. When I first saw it, I thought it was an immature dragonfly, perhaps just emerged, because it didn't move at all. But it really is some kind of kagerou, of which there are 10 species in Japan, with 109 different kinds. It's a dayfly or ephemera. It has two long thin tails, and may live only 2 or 3 days as an adult, or even only half a day.