Mid/Long-Term Shinai Storage

Hi folks,

I found myself in Japan the other week and took the opportunity to stock up on four good-quality shinai thanks to the weak yen. I’m planning to use two in rotation and keep the other two as their replacements.

Beyond loosening the tsuru and keeping them somewhere relatively stable (I’m in the U.K.), are there any other recommendations for how to make them last as well as possible for, say, a year?

Thanks