KAKIGORI will help you to survive the August heat
Kakigori is a mountain of grated ice cubes with something on top of it to give it taste. Simple Kakigori comes with some kind of sirup (the chemical type - with fluorescent blue, green, red, yellow color).
More elaborate ones comes with Uji tea, like the one in this picture, or other tastes like sesame, even coffee. And why not? While the colors do not look very appealing to us Occidental, it makes the eyes of every Japanese glitter so much you can see the Milky Way in their eyes.
It is quite sweet actually, because with the green tea part, you also have a sweetened milk , sweet red beans and "shirotama" - literally "white balls" - it is chewy rice balls. It has no real taste but it has an important role: it helps you finish the kakigori that is so sweet that you need something to atone it. Really, you need to try this before you leave Japan, you will not regret it.
So the best way to enjoy Kakigori is to be outside in the heat (stay in the shadow) and to eat it fast, before it melts away. Trust me, if you are inside, in cooled-down air, you will not enjoy it as much.
You find kakigori everywhere, even at Tullys coffee shops (the ice-cream on top is too much though so ask not to have it).
If you happen to be close to Tokyo station, go to Shin Maru Bld and eat your best kakigori ever (even if it is inside the tea house): http://www.marunouchi.com/e/shop/detail/4003
Yuki-no-shita pan-cake and coffee shops also offer kakigori. Their sweets are fabulous. There are shops in Ginza, Osaka, Kyoto, Fukuoka, Yokohama. Be ready to queue; Yukinoshita deserves it. http://yukinosita.net