Mix purple sweet potato powder and water in a small mixing bowl and set aside.
Mix kabocha pumpkin powder and water in a small mixing bowl and set aside.
Place Shiratamako and silken tofu in a large mixing bowl. As you drop the tofu in, break tofu in your hand.
Knead them all together until all are combined well and the softness is like your ear lobe.
Divide the dough into three equal portion.
Add sweet potato paste into one dough, Kabocha pumpkin paste into the second dough and black sesame paste into the third dough.
Knead them into each dough, until each colour is spread and mixed in evenly.
Divide the each dough into 6 equal portions.
Shape them into round balls with your hands and wrap them gently with cling wrap so that the balls don't become dry.
Boil about a litre of water in a large saucepan over high heat.
Add the dango dough into the boiling water and turn the heat down to medium.
Let the water simmer until all the dango dumpling dough balls float up to the simmering water surface.
Use a strainer to drain the dango dumplings out, and put them into a bowl of cold water to cool down.
When all dango are cooled, drain them out again using the strainer and place them on a plate.
Put one black, one yellow and one purple onto a skewer. Repeat the process for all dango dumplings.
Serve them on a plate with Japanese brown sugar syrup or soybean powder (kinako) *5
*1 = 1 tsp*2 = 1tsp*3 = 1/2 tbsp*4 I usually use 1 Shiramako flour to 1 tofu ratio however, all tofu are different. So you need to adjust according to the how much the tofu you use contain moisture. *5 those topping are optional and suggestions.