Though Japan was famously closed to most foreign traders for 200 years between the mid-17th and mid-19th centuries, that doesn't mean people didn't try to stop by. This small museum lays out in detailed English the 1791 attempted visit by two US ships, Lady Washington and Grace, and the locals' mixed response to the curious Western vessels anchored in their bay.
From here, walk a few minutes further to the coast to see the also curious Umi-kongō (海金剛) rock formations, shaped like pyramids and columns jutting out of the ocean.
If you're also visiting the Turkish Memorial Museum, purchase a combined ticket (adult/child ¥600/300).