Kinako 黄粉 is roasted soybean flour used extensively in Japanese cuisine: most often seen as a coating for dango and jelly-like sweets such as warabi-mochi.
Kinako has been used in Japan since the Nara era and was originally used instead of sugar. Sugar was only introduced into Japan in the 16th Century and then only for the upper classes, not being widely available until the 19th Century. So kinako is still used for traditional sweets instead of sugar.
Kinako has a unique flavor: it is nutty and slightly sweet, and its fine texture adds interest to any sweet dish.
‘Japanese Superfoods: Kinako, The Miracle Powder’ by Anisa Kazemi
‘Nine Ways to Eat Kinako’ by John Spacey
If you are really keen to learn all about kinako and its history, there is a whole book you can download:
William Shurtleff & Akiko Aoyagi, History of Roasted Whole Soy Flour (Kinako), Soy Coffee, Coffe Alternatives, Problems with Coffee, and Soy Chocolate, 2012.