In a small bowl, vigorously whisk together hot water and matcha until it is dissolved. You might want to sift the matcha first, then whisk because it tends to clump easily.
Once the matcha is dissolved, put it in the fridge to chill for about 5 minutes. This way it won’t get immediately diluted by pouring the hot liquid over the ice.
Once it’s chilled, add the matcha, pineapple juice, ginger and a couple of ice cubes to a cocktail shaker (or mason jar) and shake, shake, shake.
Then strain into a tall glass with ice and layer in the coconut milk.