Prepare a moistened plastic container and a damp but tightly wrung out kitchen towel.
Put the water, warabi mochiko and sugar in a pan and mix well.
Cook while mixing with a perforated spatula (over medium-high heat).
When the mixture has hardened that it forms a thin film on the bottom of the pan, take the pan off the heat, place it on the moistened kitchen towel and stir well.
Repeat Step 4 about 3 times.
When the warabi mochi is shiny, transfer it to the moistened container (a flat one is best). Refrigerate once it's cooled down (but be sure not to let it over-chill).
When the warabi mochi is well chilled, cut it with a spoon, transfer to serving plates and top with kinako.
You can also just add a little sugar to the mochi itself, and serve the mochi with brown sugar syrup and kinako on top.
Story Behind this Recipe
I wanted to make the warabi mochi that I'd learned how to make in a cooking class a little bit softer with dark brown sugar. I make this using Lakanto (a brand of artificial sweetener) for my mother in law, who has diabetes (I've added notes for that as well).
Don't chill it for too long. It's best to make it 3 to 4 hours before you intend to eat it.