In Yokote, deep in the snow country of Akita, February brings rooms made of winter. Kamakura are snow huts, some three meters tall, and on the nights of the 15th and 16th about a hundred of them glow across the city. Inside each one: a small altar to the water deity, a charcoal brazier, and children who call out to passersby—"Haitte tanse," come in, come in—and hand you sweet amazake and grilled mochi. You duck through the low entrance, sit on a straw mat, and discover what everyone here already knows: a room made of snow is warm. The custom is said to be some 450 years old, a weaving-together of two winter traditions—New Year prayers to the water god for a good harvest, and the snow caves children have always dug for play. The altar and the game became one thing. The huts cluster near the city hall and along the old samurai street of Haguro-cho, and the scene is best after dark, when the walls glow orange from within. Down at the Janosaki riverbed, thousands of miniature kamakura hold single candles, a field of snow turned into a field of stars. Yokote is reachable by train from Akita or Morioka, and the local yakisoba—thick noodles, a fried egg on top—is the correct way to warm up between huts. Dress for real cold. The warmth here is the kind you have to earn.