Soba Boro is a traditional Japanese cookie that is made with buckwheat flour. It is a traditional Japanese confection. The texture is said to be similar to biscotti. I have not tried it myself as i have not been to Japan. But there is a recipe shared by www.cookiecompanion.com for this. The above images show one with with ginger and gomasio and the other plain. Gomashio is made from sesame seeds and salt . It is often used in Japanese cuisine, sometimes sprinkled over plain rice or onigiri.
For more info , here are two blog reviews about this cookie from Japan: