布ナプキンは洗濯してきれいに落ちますか?

Do cloth napkins come off cleanly when washed?

yes. Linenna's detergent is specially designed to remove menstrual blood stains, so you can simply leave it on without massaging it and run it in the washing machine.

This article explains in detail how to wash cloth napkins. https://rinenna.jp/articles/1179/