How to open the Mikatagahara locked gate in Nioh 3

The Mikatagahara locked gate in Nioh 3is confusing almost everyone who encounters it in Team Ninja’s latest Soulslike, because this area — recommended for players at just level 20 — is otherwise fairly small. With a single path running from the south and bending around to the east, and just a few points of interest to hit along the way, the locked gate heading north looks like it should be able to be opened.