This is the earliest version of the Hi-Polymer lead that was released by Pentel. For stationery enthusiasts who appreciate its value, how about it? I don't think it will ever be available again (it has never been listed on Yahoo Auctions or Mercari). There are no 50 yen ones in particular. It reflects the prices of the time. Early 1970s - Hiragana "Pentel" logo 50 yen list price - Blue clear case specification (dead stock 1 dozen) The earliest design with the JIS mark, the pinnacle of the collection.