The Japanese summer is hard to bear. The temperature itself is not extreme (in my view, that is) but the humidity presses down on people more than is comfortable. To help them surviving the heat, the Japanese have come up with a very special type of summer clothing, called the jinbei. 
Essentially it is nothing but a kimono, cut off at the hip, with shorts added to at least partly cover the nether regions. There is no obi belt for the top; instead, four ribbons are attached that are tied together, which makes the top sit rather loosely. The cloth is usually soft cotton dyed in various hues of blue, mostly with a subtle stripe pattern.
If you look closely at the picture above, one thing that makes the jinbei so cool to wear are the open stitches between the sleeves and the body. This particular one has the same open stitches at the side of the body as well, but the majority of jinbei I have seen do not have them. Also, there are holes underneath the armpits where the seams have been left completely open – this is a standard feature of women’s kimono as well, by the way. These planned holes allows for extra circulation of air at a time when every bit helps.
Wearing a jinbei is very comfortable even in the biggest heat, but: it is a men’s garment, and even men are supposed to wear it only at home. It is not considered in good taste to wear it anywhere outside of the house especially when mingling with other people, but at Gion matsuri’s yoiyama, some young people wear them regardless. Nowadays there are even jinbei for women, in much more flashy colours and with the obligatory flower print.
However, personally I prefer the subtle patterns of the men’s jinbei, and I will probably go out and buy myself another one since they are so much more comfortable than shorts and T-shirts.