When was cremation first introduced on a large scale in Japan?

The first record of cremation in Japan was in the second half of the 6th century, but at that time burial was still the mainstay, and there was a ban on cremation in 1873, but it was abolished in 1875. Later, as technology developed, cremation slowly became more common, and by the end of World War II, it had spread throughout the country. Now Japan is almost 100% cremated (except for a very small number of outlying islanders).

Addendum: There is no legal requirement for cremation in Japan, but the government encourages it. Only Tokyo and Osaka have ordinances against burial.