What is "kinkeshi"

Kinkeshi (キン消し, lit. "KinnikuEraser") is an extensive and popular line of collectible erasers, an instance of the modern Japanese popular culture institution of keshi. The keshi it includes are monochromatic and derived from the Kinnikuman (キン肉マン) anime and manga franchise, whose primary motif is professional wrestling.

The line was launched in Japan in 1983, and licensed in 1985 for the American market as M.U.S.C.L.E. (reflecting Kinnikuman's English title of Muscleman). M.U.S.C.L.E. used a harder rubber than Kinkeshi; its U.S. sequel, Ultimate Muscle, had a small release of about twenty Kinkeshi, though a larger run of figures using a plastic softer than M.U.S.C.L.E. but not eraser-like was released exclusively in the USA.