Japan has many kinds of unique vending machines. Recently I saw the ones selling bananas, canned hot soup and canned hot ramen each.
However, I had never seen a vending machine for SIM cards until I found one in a Gigazine article. It says internet provider So-net has installed a SIM vending machine in Kansai International Airport (KIX), Osaka.
So-net is a subsidiary of Sony and works as a MVNO for NTT docomo, Japan's largest mobile carrier. These SIMS are for LTE and 3G networks.
This machine may be selling data only cards at this moment.
The article in Japanese.
http://gigazine.net/news/20140422-so...epaid-lte-sim/
So-net lte website
http://www.so-net.ne.jp/prepaid/en/index.html
Machine map.
http://www.so-net.ne.jp/prepaid/en/b...ex.html#shop01