Sellers can send offers to users that are viewing their items, or adding those items to carts or to watch lists.
If all or most of the recent items you have viewed are shipping from Japan, then all or most of your recent offers will come from that same pool of sellers selling those items from Japan.
Is it possible that because of your recent trip you have your account set to show you items that specifically ship to Japan in your search results? Change your sort order to "Nearest first" and see what location is shown, and update it to your current location if necessary.
