Having never used Rinkya, I don't know what they 
use to ship.  Are you talking about those plastic 
hinged boxes?  If so, you can get them from any 
stationary or 100 yen shop in Japan.  I imagine 
that most Japanese people haven't even considered 
buying or selling them online since they're so 
readily available here and there isn't a demand 
overseas that I know of.  -_- Don't know where 
you can buy them easily, sorry.


Jennifer