I don't live in Japan and can't get things shipped from Japan to here.
Is there anything that I could use as a string in a pinch? Like things that can be bought at hardware stores, etc.
I have run out of 2nd strings and have a show in Friday.
I have used (and still use for that matter) nylon guitar strings on my shamisen before, both for the first string and the second string. It has a warmer and slightly different tone than twisted silk strings, but I think they work great. I forget the exact sizes I use for the first and second strings, but they should be standard nylon classical guitar string sizes - I just brought in the silk strings for size comparison when buying them at a local music store. They are dirt cheap, and while a bit on the short side, they last forever. I have been using them nearly exclusively now on my cheaper shamisen to save money on silk strings. I have also made my own twisted synthetic strings from nylon, polyester, and kevlar as well, but these aren't really something that someone would use in a pinch, since it takes some extra equipment and a lot of practice. But I would say that monofilament nylon classical guitar strings are a great alternative to silk strings, regardless if you need them in a pinch or not.
I'm convinced that nylon classical guitar strings are simply the lowest grade fishing line with a 5000% markup