Hokusai’s work method
 

 All the drawings were made on usugami, a very fine paper whose main feature is that it remains transparent even when several layers are superimposed. This characteristic renders it irreplaceable for making copies using the tracing technique. At that time, Hokusai’s working method  was mainly based on the transparent nature of usugami. It enables a drawing to be accurately copied while adding any desired improvements. This is the entire purpose and reason of this series of  "creatively traced"  preparatory drawings.

 Thus, when embarking upon a new project, Hokusai would most often start with a sketch of the main character of the scene, which he would draw in the least structured way possible, with a rapid, cursive stroke, without regard for layout (the ichiji shita‑e). These first sketches clearly show an obvious intent to prefer imagination to form and structure. As most of these sketches were made on areas of a sheet that remained free on a drawing made a year or two earlier, this could indicate a habitual practice that would naturally produce studio image archives.

 Once the preparatory sketch was finished, it was ready for use as a basis for the first scaled drawing for the woodcut  ( the shita-e). For this next stage the sketch would be set on a guide of the shape and size defined by the four sides of the frame of a print in an illustrated book and its inside margin. This guide enables the artist constantly to keep the exact limits of the print, which he needs to abide by, in sight, and most particularly the limits of the inside margin, which is so difficult to incorporate in the composition. Therefore, Hokusai would place the new sketch on a guide, and, on top of it, as a third layer, add a new usugami sheet.

The drawing ready to be copied for the final work, as it appears between the bottom page guide, and then through a new sheet of "usugami".

The transparency of this paper, even through a thickness of two layers, allowed him carefully to lay out the sketch on the guide and then recopy, or, rather, redraw - for not only does this procedure provide a first layout for this new drawing, but by redrawing it, the artist uses a careful stroke that is close to the final version. Once this main part of the new drawing was finished, Hokusai would remove the sketch from the pile of tracings, and, always working on the guide, he would begin to place the first elements of the décor. At that moment Hokusai would above all focus his attention on inventing a strong, well-balanced composition around the freshly installed central character. Now the work again becomes creative, and fast, light strokes are again the most suitable and the most frequently used, except for the important elements, such as the composition’s structural lines or the details to be conserved on the next drawing, which he would carefully trace with a strong stroke and very dark, black ink. Certain repetitive decorative details can be developed very precisely and yet economically as stock images.

The last drawing, the hanshita-e, revisits all elements already in place, corrects the layout one last time, adds the text, callouts, a frame, and gives the entire tableau its final elaborate features.
It goes without saying that as this last drawing is meant to be glued onto the wooden board that will be used to produce the woodcut, and will therefore be destroyed at the same time as it is engraved, hanshita-e are not normally preserved, except perhaps as a result of a copied or abandoned project. On the other hand, nothing can be easier than finding out what it looked like – after all the resulting print is a faithful copy.

The discovery of the process used for the creation these drawings initially provided evidence that they were indeed originals stemming from Hokusai’s studio. But this also made it possible to assign to this artist, who was already considered to have been the inventor of the word “manga”, his rightful place as a forerunner in the technique of step by step improvement of his sketch by means of tracing paper, still commonly used today by numerous manga artists.