Gokujo Yuen ( superb oil smoke ) sumi ink sticks, faint bluish series ( 古梅園 極上油煙墨・薄青系 )
This light blue ink is made by extracting oil smoke from rapeseed oil and the pigment most suitable for blue ink color from plants and trees.
It avoids extreme coloration and can express a black color with astringency and calmness.