For our Japanese readers, here are a couple of resources to help introduce you to the theremin. First up is the Adult Science Premium Theremin (translated) from Adult Science Magazine (the same folks who introduced the world to the Gakken Mini Theremin). It currently sells on Amazon.co.jp for 9780 Yen, or about $114 USD at the time of this posting.
Next up is the Theremin Learning Book by SATO Sha Megumi. It's also available at Amazon.co.jp and currently sells for 2709 Yen, or about $31 USD.
If you have either of these products and would like to write a review for Theremin World, please get in touch.