Those who are curious about the tools part..
He uses Mitsubishi Uni pencils. His recommendation of sharpening the pencils "[Make the exposed pencil lead long] By making it sharp and long, the sharp will continue and it is easy to re-sharpen"
His YouTube video [1] shows his collection of pencils (the various grades) and the meticulous attention to pencil sharpening - which seems to be in two stages, the first is using a normal mechanical pencil sharpener and then the second stage is handcrafting the length of the lead.