I think I heard of it and saw a video about it on youtube then completely forgot it exists. I should know a bit about it because it's Hudson and some of the Japanese Bomberman games on gameboy supported it. Enjoyed reading a bit about it before bed lasts night. Very cool stuff. I wonder how much it would cost me to get some of this junk on my shelf to display. I have a soft spot for Hudson stuff. I was also thinking about rounding out some of my NES collection with some Hudson titles. A few of them are fairly inexpensive. My main interest in Lode Runner is the Bomberman sprite in the game.
However, if you do a search every now and then on American ebay, it could show up, and many would skip over it since they have no idea what it is. I've scored some obscure stuff that way. Unfortunately, the Japanese sellers are getting smarter and are evaluating the market value. They might keep track of ended listing and set the value around the last ended price.
You might fare better on the Japanese Mercari site ( https://www.mercari.com/jp/ ). It's kind of like ebay / any other online marketplace; however, the buyers and sellers on there are encouraged to talk to each other before they hit the buy button to confirm the sale or bargain for a lower price.
A problem arises when a seller demands talking before the sale. Another problem is that purchasing items through there takes more time via the avenues I use. It usually takes some time to put money in the online spot it needs to be before the sale can go through. In the meantime, a Japanese native can swoop in and score a deal.
The two services I use for Mercari Japan purchases are Goody-Japan (GJ) and Buyee. Buyee seems easier; however, it usually costs a lot more than GJ to ship an item. GJ is excellent with price of service and shipping, but you have to Paypal the money to them first (instantaneous) and then place the order through a form email while logged into their site. It may seem sketchy, but it's like an anonymous friends coordinating a sale on the other side of the world for you. You can even ask them to bargain. GJ takes more time to complete the sale. Hence, your item might go bye bye if another person sees your deal.
When using any Japanese proxy service, I recommend paying via Paypal. It's a lot faster and there are no hiccups with address or zip not matching your card. Even though you can set the name / address info on the proxy service site, make sure your Paypal account is setup with all the correct info.