If you are in the US, your order is likely to have been split between US and Japan inventory, especially if you purchased a bundle or large quantity of issues.
This is because we do not currently have a full inventory in the US, and Japan Post imposed a ban on US-bound airmail since April that has lifted as of 11 October 2020 (see Which countries do you ship to?). We will be shipping the remainder of your order as soon as possible, though please note we expect severe delays and it could take up to 6 weeks.
The issues we have in US inventory are listed here (please scroll right the way down).
If you are not in the US, it sounds as though there may have been a mistake. Please write to us and we shall sort it out for you.