I was walking to Wazuka tenmangu shrine the other day when I noticed several white diamonds painted on the road. These diamond-shaped markings also appeared on a street near Kohfukuji temple in Nara. Now that I google earthing over Japan and realise that they are almost every where in the country =]]
According to Japanese Road Signs and Markings, a white diamond indicates we are approaching a pedestrian crossing. They are painted only when a pedestrian crossing is not highly visible to road users, for example the crossing is around the corner or on top of an uphill street. In some cases, shadows and other lighting phenomena make the crossing hard to see.
Not only in Japan, we can see these white diamonds on the streets of China, New Zealand, England and many other countries because of an apparent international uniformity and standardisation (of course only to some extent).