Five hundred miles from the glitz of Tokyo floats Hokkaido, Japan's nothernmost island, for years inhabited only by fierce tribes, myths, and shadows. Martha Sherrill travels into the fabled snow country to find a unspoiled place where the seafood is bountiful, the bathing is restorative, the skiing is epic, and the soul of old Japan still lives on

As I fly over Hokkaido, the island looks slumbering and still. Our plane descends into whiteness. All of life—the city streets and train tracks, the dairy farms, the silent volcanoes and boiling hot springs—lies beneath layers of snow. It is a frozen winter world, a mysterious land of submerged identity.

Snow falls almost every day in the winter on the northernmost island of the Japanese archipelago, making its largest city, Sapporo, one of the snowiest in the world, snowier than Helsinki or Oslo or Anchorage. The peak comes in February, around the time of the Yuki Matsuri, or Snow Festival, when two million people, mostly Japanese tourists, show up to party— if the planes are landing and the roads are clear.

Now, just three weeks later, the snow castles in Odori Park have melted and refrozen into blurry shapes. The streets around the train station are calm, the beer halls quiet, and the taxi drivers in their boxy white sedans are lined up by the dozens with not enough to do, like the schools of herring in the Sea of Japan that returned this month to spawn.

In the early morning, we take one of those boxy white sedans away from Sapporo and head to the old harbor town of Otaru, an hour away. I've come to prefer rural, out-of-the-way corners of Japan, places where life is still lived close to nature and the ancient traditions endure. Tokyo, Kyoto, and other big Japanese cities are exciting and full of energy, but visitors find it difficult to get beneath their surface and tap into their real life—the eternal Japan that is at once ancient and modern, and as vital as a heartbeat.

My cousin Leslee nudges me. "Look at that!" she says, pointing to the roadside. The haisetsu fu, or snow workers, have finished plowing and shoveling and sweeping. What remains is a perfectly plumb sheet of snow. No lumps or random splatters. It is as straight as drywall. In Japan the snow is managed, as is all else, with a heartbreaking mix of artistry, precision, and care.

"How is that wall of snow made?" I ask our taxi driver, Tanaka-san, a handsome grandpa with a dark business suit and a gentlemanly manner, whose cab is so tidy that the upholstery is protected by lace.

"Special machine."

Leslee makes the universal sound of appreciation, ahhhh. She is traveling for the first time in Japan, a place that has fired her imagination since she was a young girl. (When we were growing up in California, she arrived for Thanksgiving dinner at our grandparents' house one year wearing a kimono.) But I was the one who got to live here briefly, a decade ago, and returned more recently to research a book set in the snow country. Now, arriving in Sapporo from two different coasts—Leslee lives in Los Angeles and I live on Cape Cod—it's a thrill to get to show her the place that I've come to love so much.

As we explore southwestern Hokkaido, a land of volcano clusters, rugged shorelines, deep snow, and hot springs, we'll be staying in traditional country inns, or ryokans, which offer a calm, almost timeless setting. We will be sleeping on the floor, eating traditional Japanese cuisine, and, since I am nursing a back injury, making full use of the communal hot springs baths. My task will be to guide my cousin as she submerges herself in Japan, literally and figuratively. Her task won't be so terrible either: to ski as many volcanoes as we can find.