This video from the Netherlands says about itself (translated):
July 4 2018
An unknown and completely unique masterpiece by the Japanese artist Kawahara Keiga (c.1786-c.1860) was recently discovered and purchased by the National Museum of World Cultures. Conservators found the human height folding screen (eight panels of almost 5 meters wide) of great artistic and historical significance in private possession. The work of art shows the bay of Nagasaki with the Dutch trading post on the island of Dejima in 1836. It will be a key piece in the Japan collection of Museum Volkenkunde [in Leiden, the Netherlands].
See also here.