Recently acquired a Niji X-10 and it is seen here with a Tombow X-1 ballpoint (probably part of the ‘Lively’ series because of the L02 mark).
I found out that NIJI is still in business and wrote in to ask about the X-10. Lo! I got a reply from a lady at Niji:
“Thanks very much for your inquiry. I reached out to the former owner of Yasutomo and received his kind reply:
"Wow, this pencil goes back to around 1990 because I believe the company was still located in Brisbane near Daly City when we brought this pencil in. This product may be in one of the old catalogs.
At the time the technology of mechanical pencils developed a system that by pressing the tip of the pencil, the lead would advance on its own. Kotobuki may have invented this system? A supplier in Japan produced this product in a metal barrel and we named it the X-10. I want to say we set the retail at $15-20 but it may have been $10 (therefore X-10) but I am not positive.
Unfortunately the pencil did not do as well as we hoped and after a couple of years we discontinued the item. Also, the factory went bankrupt. So not many glamorous details to tell you about X-10 other than I thought it was a pretty cool product but the price may have been the problem at the time."
And that’s all I got.