At the base of Mt. Fuji is Aokigahara, a forest most people only know from movies. When I finally stepped inside, it felt strange at first—quiet, dark, and colder than expected. But with a local guide, I started to see another side: mossy roots, hidden caves, and a calmness that made the place feel alive.

Formerly walked by Japan’s emperors themselves, the ancient pilgrimage routes of the Kumano Kodo have long been on the list of those...