Mix the matcha tea with 2 tablespoons of milk in a cup until smooth. Peel the banana, cut into small pieces and place in a tall container. Add milk, agave syrup and the mixed matcha powder. Puree with a hand blender until creamy.
Depending on how sweet the shake should be, you can vary the amount of agave syrup. For a mild taste use only 1 g of matcha tea, for a strong, tart taste 2 g.