Deep in the mountains of eastern Aichi, the small town of Toei spends its winter awake. From early November to mid-January, ten hamlets take turns holding the Hanamatsuri — the "flower festival," though no flowers appear. What appears instead: a cauldron of sacred water boiling at the center of a dirt-floored dance ground, some forty ritual dances performed straight through the night, demons in carved masks shouldering great axes, and a crowd chanting "teehohe, tehohe" with the dancers until dawn. The rite is seven centuries old, an Important Intangible Folk Cultural Property, brought here — it is thought — by mountain ascetics in the Kamakura era.

The timing is the theology. Held originally in the old lunar eleventh month, the festival falls at the year's darkest hinge, when the sun itself is believed to weaken; the boiling water, the dances, the sleeplessness all exist to reawaken the sun, the soil, and the human spirit together. The climax, the yubayashi, sends scalding spray from the cauldron over the audience — to be splashed is to be reborn for the new year. It is the twin of the Shimotsuki Matsuri in the Toyama valley just across the mountains in Nagano; connoisseurs of winter kagura do both.

Visitors are welcome at most hamlets (a small offering is customary, returned with local courtesies), and by three in the morning, chanting along stops being optional. Toei is about two hours from Nagoya via Toyohashi and the Iida Line. A depopulating mountain town that, a few nights each winter, becomes the most wide-awake place in Japan.