Hand Tools Archive
While high speed steels (HSS) may have high amounts of carbon, it has been my experience that when a manufacturer advertises "high carbon steel", they specifically do NOT mean HSS.
HSS do not lose their temper until they gets almost red hot. So they are preferable for tools like drill bits which can get quite hot in use. Generally they are also more abrasion resistant, making them useful for things like jointer and planer blades, but less useful for hand tool blades because they are harder to sharpen.
It is pretty unlikely that mujinfang would be supplying HSS blades. It would be unnecessarily more expensive or difficult for them to make, and they might get a lot of complaints from users who find their oil stones won't abrade the blades.