There are other famous and well known natural Japanese wood finishing products, like bengara, red ochre (also used in ceramics)... 
...and pine soot, using the carbonized resin rich tree stump (another forestry by product). It was popularized largely in the 12th c. when the imperial court made it fashionable. Dissolved in alcohol, diluted in water and given a linseed oil final finish it can be used indoors.
Of course the king of interior wood finishes is urushi lacquer. Expensive, but it last virtually forever, easily maintained. It is so safe doctors recommend it for baby eating utensils. You can polish it to a rich, mirror-like surface. Can't use it outdoors though.
