Zachary didn't pay much attention to what Yara said on this point; after all, when the disaster first struck, he had used the space in the Cave to stockpile an abundance of supplies. Then, as the Cave was upgraded and Canary moved into the Cave, both agriculture and animal husbandry were well underway, so the issue of physical goods wasn't really a problem.
As for so-called Credit Points, they are essentially the transactional currency used in Kyoto.
To be honest, the Imperial Court originally wanted to continue using the pre-disaster paper money as circulating currency, but due to various reasons, they ultimately abandoned the use of the former paper money.
