Cut mango and purée in food processor. Measure out 1 2/3 cup and reserve balance for other use. Place mango purée back in processor.
Sprinkle tablespoon of gelatin powder over hot water in a small bowl and allow to soften for a minute or two. Whisk to dissolve. Allow to come to room temperature and pour in with mango purée. Process with a few pulses and set pour into clean small glasses or bowls. Refrigerate for 1 hour to set.
In a small bowl whisk together the matcha green tea powder and powdered sugar. In a saucepan add the heavy cream, sugar and matcha mixture. Stir to dissolve the sugar and matcha and bring to a boil. Turn off heat and allow to come to room temperature.
Again, sprinkle tablespoon of gelatin powder over hot water in a small bowl and allow to soften for a minute or two. Whisk to dissolve. Allow to come to room temperature and pour into the matcha cream mixture, stirring to mix thoroughly.
Pour this mixture over the set mango purée, return to refrigerator and chill until completely firm about 2 hours.
Dice the pineapple and top each chilled panna cotta and serve.