This is a very rare style of Japanese matchlock, with three separate barrels on a revolving axis. It has all the design and decorative elements of a tanegashima musket, but built more as a self-defense piece for home or perhaps when traveling by palanquin. Think of it like the Edo-period Japanese equivalent of a Howdah pistol or coach gun. The barrels are approximately .40 caliber (~1.5 monme) and smoothbore. Each one has its own set of sights and priming pan and cover. They were held in place by a flat spring and friciton, although the spring is worn out today. It’s hard to give an exact date to this piece’s construction, as Japanese firearms design changed very little between the early 1600s and the mid 1800s.

Full video on the tanegashima:
https://forgottenweapons.vhx.tv/videos/tanegashima-4k