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Are they butted?
There are butted ones and bladed ones. I suppose it's not beyond the realms of possibility that either Hoshi or Asahi have, at some time in the past, issued NJS certified plain gauge spokes, so @Husy could research that and if it turns out to be the case he could pay some lavish sum of money to obtain some NOS NJS spokes of a type suitable for shortening, and then void the certification by shortening them.
He can't go for it, because NJS spokes are too long.