The steel series called kigami/shirogami (yellow/white paper steel, high purity carbon steels in different grades), aogami (blue paper steel, a tungsten alloyed tool steel series), aogami super (a refinement of the aogami series), gingami (silver paper steel, a rudimentary but pure and apparently precise stainless series) are commonly used for quality japanese hairdressing, kitchen, gardening, woodworking and shaving tools.
Such tools are, in the west, usually marketed as very traditional.
Nowadays, it seems these steel types are proprietary to the hitachi subsidiary "Yasugi Special Steel Works"
When were these steel types introduced? English language internet research yields no clues except that YSS was founded in 1899 and merged multiple times, and that some rather old YSS-steel based razors exist with S2 and A2 as part of their inscriptions, and that these steels use some kind of electric crucible process and are made from iron sands, and that the highest carbon grade of "white" steel (shirogami #1) is considered similar to traditionally made "tamahagane" sword/knife steel in material properties.
Were these steel types an invention of YSS; if not, who introduced them when; if yes, when did they introduce them? What preceded them in the relevant markets?