Ok this requires a metric, you know what, load of patience but don't be put off as you will be rewarded with an elixir unlike anything else you have ever tasted before.
You will get a decent, if immature, tasting result after 3 months stored in your deepest, darkest cavernous area of your abode but for best results just let it be for at least a year and preferably longer.
I also make mine with a combination of shochu and other drinks such as calvados, brandy and rum which plays to an extremely warm welcome.
1 kgJapanese unripe plums
200 grock sugar
2 litersshochu (35%)
1Dissolve sugar in alcohol.
2Put cleaned plums into sterilised storing vessel and pour in the alcohol/sugar mix.
3Put a label on it and forget about it for a couple of years!
Im lucky to have a good neighbour with a couple of trees full of these beauties but they are everywhere to be found in june.