Maybe due to the machine translation, the description on the item by shop is incomprehension. Though, don't hesitate to ask the shop to confirm you questions.
Most items shows below are only one though if it is sold out find from the shop's top page here at the bottom of this page.
http://domoarigatojapan.weebly.com/blog/how-to-use-rakuten-global-service
But maybe not needed because it's easy to do.
Hope you to enjoy!