In a bowl, combine joshinko, shiratamako, and sugar.
Add the hot water into the bowl little by little, mixing well in-between. Keep adding water and mixing until the "dough" smooths out and the texture is about the same texture as your ear lobe. You can knead with your hands as the dough comes together.
Divide the dough into 3 equal parts.
In a small bowl, put in one part of the dough and 1 drop of food coloring. Knead until the color is distributed evenly throughout.
In a small bowl, put in one part of the dough and the matcha. Knead until the color is distributed evenly throughout. Feel free to use a couple of drops of hot water to help the matcha disintegrate evenly if the dough becomes a little dry.
Separate each colored dough into 8 even pieces and roll into small balls (so there will be 8 white balls, 8 pink balls, 8 green balls).
In a pot on the stove, boil water. Drop in the white balls to cook first. Stir carefully occasionally to make sure they do not stick to the bottom. Boil until the balls float to the top (approximately 8 minutes) and boil for one more minute. Then remove the balls from the boiling water and shock in an ice bath.
Repeat the cooking and ice bath process for the pink balls, and then the green balls. Make sure to cook them in that order (lightest to dark) in case there is any color leakage.
Remove the balls from the ice bath and lightly dry.
Skewer the mochi onto bamboo skewers. Usually it's green on the bottom, then white, then pink.
Enjoy!