Just saw this amazing coin-op pong console purportedly from a hot springs resort show up on Yahoo Auctions in Japan. I've copied photos over here for when the auction is over and the page inevitably disappears.
The console appears to be manufactured by Hagiwara Electric (founded 1958, still exists) and distributed (?) by Toyo Bussan, but the chip inside appears to be Atari's original Super Pong chip (I'm guessing "L.S.I." refers to some kind of international licensing agreement). I can't seem to find any other reference to this unit on the internet, though admittedly I've not spent a lot of time looking on Japanese-language sites.
Below the photos I've posted a (possibly bad?) online translation of the listing -- if anyone wants to improve it, please feel free.
The opening bid is 100,000 yen... but I imagine one would recoup some of the final cost from the 100-yen coins still locked inside!
Once upon a time, in a hot spring resort, was this nostalgic game machine to play a few minutes for 100 yen. I think that the game is decades old, but it's been kept in a really nice, clean state as seen in the photographs. A protective seal is still stuck onto the plate that explains how to operate the console. It powers on when 100 yen is inserted, and one is able to play for approximately 10 minutes (we did not measure the exact time). To play longer, add an additional 100 yen. (It seems like one can add up to 400 yen at once.)
Plug it in, insert 100 yen, the power indicator will light up, and the game will be displayed.
Four types of games can be played, and switching between games is possible while the power indicator is lit.
Sound is output through a speaker in the center of the unit.
Video is output through RF. We connected to an antenna terminal on a VCR, and its video was output to a TV screen. If you want, we'll include the VCR shown in the photo.
There's no key, so we can't see/show the inside of the unit (and hundreds of yen are inside).
One could possibly pay a locksmith shop to open or break the lock.