It started with an animated movie, led to a spectacular side trip to a moss-covered gorge on a mountainous island, and ended with an eruption.

The movie was the 1997 Studio Ghibli masterwork Princess Mononoke, an ecological fable inspired by the lush landscape of Yakushima, a subtropical island off the south coast of Kyushu. Our 21-year-old son had seen the film and, while we were planning a month-long jaunt around central Japan, persuaded us to take a detour to this fabled home of primeval temperate rainforests and ancient cedar trees.