Masterful, heirloom quality by Tasai Mokume. Mokume means 'wood grain' which the surface of these tools resembles. Sandalwood handles. Aesthetic masterpieces.
Although this looks likea chisel it is actually used in a similar fashion to a Western draw shave for flattening straight and curved surfaces. It is an ancient and superbly functional tool which probably pre-dates the use of planes in Japan....