There were very few sources of sugar in Japan until the country was flooded with Snickers and friends after WWII. These persimmons were a real treat in days long ago. The astringent ones must be semi dried in the sun before they are edible. The tartness evaporates and you can find countless varieties of these naturally sugar-coated candied persimmon jelly fruits made with this basic sun dried technique all over Japan.
It is these astringent types that are the source of a tannin when they are still green in August. The simplest way to use the fruit to dye is to simply grate it and squeeze the pulp and paint the sticky tannin heavy juice onto whatever it is you want to dye. It should absorb deeply into the material or it will simply flake off after a few hours in the sun. After coating the juice in/on, simply place it in the direct sunlight and wait until it turns golden brown. You can hang it or place it flat on the ground. The point is to get as many direct rays and heat as quickly as possible. (This works on paper as well.)
Japanese used the persimmon dye as a simple waterproofing for umbrellas, tools etc. and as a coating to make katazome stencil paper. In the past few years, the price of the bottled tannin has gone down and it seems everyone is dying something with it. Besides being a little messy to work with, taking time and needing good weather, it is relatively easy to use and the results are usually good. There are no 'expert' persimmon juice dyers like there are with indigo and other natural dyes. There has been no 'bible' or extensive research of it's history and usages been published as far as I know.
Takeshima san and I took Geiger for a walk and stumbled upon some persimmons fallen from a tree and we quickly gathered them and took them back to the house and I showed her how to process them. She was a little leery of how simple the process was as there is a rumor out there that it is tricky to use.