Prepare martini glass by submerging the top of the glass in ice to wet outside of glass. Sprinkle the outside of the martini glass with green tea powder. Prepare green tea by brewing in water, let it sit for 15 minutes. In a cocktail shaker add ice, raw sugar, lime juice, vodka and 6 ounces of green tea. Shake and strain the cocktail and pour into martini glass. Garnish with Japanese mint.