Nashiji refers to the small whitish dots that look like the dots on the skin of a pear (nashi in Japanese). The dots have stronger cutting strength inducing faster finish. Kiita (yellow board) is THE most highly regarded colour of Nayayama stone, next comes the Asagi (it literally means faint yelloe, but it means light blue). It is often called "Tamago (egg)" colour.
You can see in the back a bit of Asagi (light blue) is showing. It has been decorated by chiseling. Sign of high quality stone. The side has the skin attatched as well.