On the fifteenth and sixteenth of December, at the summit of a mountain north of Hamamatsu, Japan thinks hardest about fire. Akihasan Hongu Akiha Jinja stands at 866 meters, the head shrine of some four hundred Akiha shrines across the country — the same name, by most accounts, that Tokyo's Akihabara borrowed. The god enshrined here governs fire itself, and so the pilgrims who climb are often professionals of the flame: firefighters, power-plant workers, cooks.

The festival's heart arrives at ten o'clock on the night of the sixteenth, when every light in the shrine is extinguished. In the sudden dark, priests perform dances transmitted only here: a dance of the bow, to divine the coming year; a dance of the sword, to cut away impurity; and finally the dance of fire, torches lit from the shrine's inner flame, whirling against the winter sky. If the night is clear, the stars above the ridgeline are astonishing. It is very cold. Nobody seems to mind.

The upper shrine is reached by road, about forty minutes' drive up from the Tenryu valley, or on foot from the lower shrine, a climb of ninety minutes to two hours. December nights at 866 meters demand serious layers. The torches used in the fire dance are later given to visitors by lottery, as amulets against fire for the year ahead — a souvenir that is also, in its way, a promise.