This is the entrance to hiking Mt. Myogi which is only recommended for those who are highly experienced. Make sure to pray hard before you attempt the hike.
Otherwise, it is a really beautiful shrine and there are also beginner friendly trails too.

About:

Myogi Shrine, located on Mount Myogi in Gunma Prefecture, is a historic shrine with buildings dating back to the Edo Period. The shrine is nestled amidst impressive rock formations and offers a steep hike up to the main shrine building, which dates back to the 1700s. Despite facing natural perils like landslides and fallen trees, Myogi Shrine remains a must-visit for those seeking an extraordinary mountain shrine experience in the land of the tengu mountain demons.