Hamanaka's Keyaki Kyodai (contract Sisters)

Hamanaka no Keyaki Kyodai: A Rare Folk Custom of Sworn Sisterhood in Yamagata

In the small coastal hamlet of Hamanaka, nestled at the mouth of the Oguni River in Tsuruoka City, Yamagata Prefecture, an extraordinary folk custom has been quietly passed down for over two hundred years. Known as "Keyaki Kyodai" (契約姉妹, literally "Contract Sisters"), this tradition sees young girls draw lots made of rice straw to form lifelong bonds of sisterhood — ties considered even closer than those of blood siblings. Recognized by the national government as a folk cultural property requiring documentation and preservation, this custom offers a rare glimpse into the communal fabric of traditional Japanese rural life.

Historical Background and Origins

The exact origins of Keyaki Kyodai remain shrouded in mystery, but the tradition is believed to stretch back more than two centuries. The word "Keyaki" does not refer to the zelkova tree, as one might assume; rather, it is a dialectal corruption of "keiyaku" (契約), meaning "contract" or "pledge." The custom emerged in Hamanaka, a small settlement of roughly 70 households historically part of the former town of Atsumi in Nishitagawa District.

Keyaki Kyodai is understood by scholars as a form of "seijogirei" — a coming-of-age ceremony for girls. Elders in the community long held that once a girl completed the rituals of Keyaki Kyodai, she was considered ready for marriage. The custom also carries prayers for safe and easy childbirth, reflecting the deep anxieties and hopes surrounding women's lives in agrarian Japan.

Why It Was Designated as a National Folk Cultural Property

In 1993 (Heisei 5), the Agency for Cultural Affairs designated Hamanaka no Keyaki Kyodai as a nationally recognized intangible folk cultural property requiring documentation and preservation measures. The designation was granted under the criterion that this custom exemplifies the fundamental characteristics of Japanese cultural life in a particularly representative way. It stands as a rare surviving example of a ritual that bonded women across their entire lifespan — from girlhood through marriage, motherhood, and old age — forming an age-based communal structure that once underpinned rural society.

The Ceremony: How Sworn Sisters Are Chosen

The ritual traditionally takes place in late December, usually around the 28th. Girls aged 12 and 13 gather at the local Osaka Shrine or community hall. Senior pairs — girls who became Keyaki Kyodai in the previous one or two years — serve as guides and facilitators.

The central act is the drawing of lots. Pieces of rice straw are folded in half, and each girl draws one. Those who draw matching straws become sworn sisters. Once the pairings are decided, the girls walk together to the mouth of the Oguni River, still clutching their straw lots, and release them into the current. They watch until the straw disappears downstream, then return to the shrine grounds — crucially, without ever looking back.

On New Year's Eve, the newly paired sisters gather at a designated house, bringing bedding and round rice cakes (mochi). They exchange their mochi and eat together, then sleep side by side in a single bed. From the evening of December 31st until noon on New Year's Day, they observe a fast called "danjiki," consuming only small amounts of mochi, sweets, or fruit. This cycle of gathering, fasting, and sleeping together continues for three consecutive years.

A Lifelong Bond

What makes Keyaki Kyodai truly remarkable is that the bond forged in childhood endures for life. The sworn sisters become each other's closest confidants — helping one another with farmwork through the traditional labor-exchange system known as "yui," providing support during childbirth and illness, and serving as lifelong advisors. The relationship is considered so sacred that sworn sisters attend each other's weddings and funerals, often taking precedence over biological siblings.

Moreover, the pairs formed through Keyaki Kyodai also constitute a broader peer group. This dual structure — the intimate bond between two individuals and the solidarity of the wider cohort — supported women through every phase of life: as daughters, brides, homemakers, and in their later years. It formed the very backbone of the female social network in traditional agricultural communities.

Visiting Hamanaka and the Surrounding Area

Hamanaka is located in the Atsumi area of Tsuruoka City, along the scenic coastline of the Sea of Japan. While the Keyaki Kyodai ceremony itself is held only when eligible girls are present in the community — meaning it may occur only once every several years — the area offers year-round appeal for travelers interested in the deep traditions of the Shonai region.

Nearby, visitors can enjoy the famous Atsumi Onsen hot spring town, one of the oldest hot spring resorts in the Tohoku region. The dramatic coastal scenery along the Atsumi coast, including rugged cliffs and quiet fishing villages, provides a beautiful backdrop for exploration. Tsuruoka City itself is recognized as a UNESCO Creative City of Gastronomy, offering exceptional local cuisine including the region's celebrated shojin ryori (Buddhist vegetarian cuisine) at the sacred mountains of Dewa Sanzan.