In a medium-sized saucepan, combine fresh blueberries, water, and sugar over medium heat. Bring to a gentle boil, then lower the heat and let simmer for 25-30 minutes, stirring occasionally, until thickened.

Carefully strain half of the mixture through a fine-mesh sieve into a bowl, separating the smooth syrup from chunky bits. Optionally stir in lemon juice.

In a small bowl, measure out matcha powder and add hot water. Whisk vigorously for about 30 seconds until frothy.

Layer 2 tablespoons of blueberry syrup in a tall glass, fill with ice cubes, then pour in your choice of milk.

Gently pour the whisked matcha over the milk to float on top for a layered effect. Drizzle more blueberry syrup if desired.