How to sharpen Japanese kitchen knife (Single-ground edge)
Spread wet cloth on sink, and set whetstone which you dipped into water enough on the wet cloth.
Place blade aslant at an angle of 45° on whetstone.
Put cutting edge of front side on whetstone and raise up the back just a little as picture.
When you sharpen front side of knife, hold the knife like the picture.
Hold handle and place 3 fingers of your left hand on blade, without pressing hard, and sharpen rhythmically.
Sharpen blade in 4 partitions. Do not sharpen whole blade at the same time.
Divide blade in 4 partitions and sharpen each partition from down part of blade to tip, or vice versa, by sliding blade on whetstone. Sharpen until metal burr at cutting edge feels rough to fingertips. Then slide blade to the next partition and sharpen whole part of the blade propery.
Sharpen back side next.
After finish sharpening front side, hold knife like the picture. Place back side very closely on whetstone levelly. Divide blade in 4 partitions and sharpen each partition same as front side.
Sharpen back side by less force than front side.
Sharpen until metal burr on front side feels rough to fingertips.
Finish by wood stand of whetstone.
Place cutting edge on bottom of wood stand and pull knife toward you to take away metal burr.
Finally wash kitchen knife with water and wipe blade and handle enough with dry cloth.