Plain white wheat flour and indication for the protein content

Protein content indicate the amount of gluten in the flour and how ‘strong’ or ‘weak’ it is in use.
Basically the high-protein content flours are used for bread, and anything that needs to be stretchy, strong and flexible (e.g. dumpling wrappers) and the low-protein flours are used for more delicate things that you don’t want to be gooey and gluten-y like pastry, cake, and tempura batter.

Hakurikiko or  ‘weak flour’  is low-gluten flour.  Kyourikiko or ‘strong flour’ is high-gluten flour.
There’s also chuurikiko (中力粉）which is ‘medium strength’ flour.

Hakurikiko |  薄力粉    7-8.5% protein
Chuurikiko |  中力粉    8.5 – 10.5%
Kyourikiko |  強力粉   11.5 – 13.5%

For comparison here’s a chart of American flour types:
Cake Flour –     7-10% protein
Pastry Flour –   9%
All-Purpose (AP) Flour –  10 – 12%
Bread Flour  – 14 – 16%

In France flours are numbered. The equivalents are:
T45 – for cakes and pastries
T55 – all-purpose, used for soft crumb baguettes and other white bread
T65 – used for ‘pain de campagne’ and other sturdy breads

Flour labeling and numbering differs by country and region, so the best  bet if you’re trying to recreate a recipe from somewhere else is to look  at the protein content if it’s indicated on the nutrition label, or see  what the flour is labeled as being suitable for. See →  Flour

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