A Kaya Tree That Twists to the Left
In the hamlet of Ohara, set among the mountains of southern Miyagi Prefecture, a single evergreen conifer rises roughly 18 meters above a quiet hillside. Its trunk measures about 2.05 meters around at chest height and 2.75 meters at the base, where the roots spread into the slope. To a passing visitor it looks like a venerable old kaya, the Japanese nutmeg-yew found across much of central and western Japan. What distinguishes this particular tree stays hidden until its seeds ripen, and then it shows itself: the seeds spiral counterclockwise.
This is the Hidarimaki-gaya of Ohara. The name means, plainly, the "left-twisting kaya," and the twist is not poetic license. It is a measurable trait of the fruit, and a rare one. The tree has been a national natural monument since 1942.
Kaya (Torreya nucifera) is a slow-growing member of the yew family. Ohara sits close to the natural northern edge of its range, which makes any large specimen here unusual to begin with. A large specimen that also carries a botanical peculiarity is rarer still.
Spotted by a Village Schoolteacher
The story of how this tree came to be recognized begins around 1924, with a man named Saito Shiroji. Saito was the principal of the local elementary school and an amateur botanist with a careful eye. Examining the kaya growing near the village, he noticed that its seeds did not look like ordinary kaya nuts. They were larger, and their surface ridges ran in a consistent spiral.
What Saito had found matched a variety that the botanist Manabu Miyoshi had described in the early 1920s, recorded under the scientific name Torreya nucifera var. macrosperma. The Latin macrosperma means "large-seeded," and that is the heart of the matter. The left-twisting kaya is not a separate species but an uncommon form of the familiar tree, set apart by its seeds.
Recognition followed. On October 14, 1942, the Ohara tree was designated a national natural monument, and the city of Shiroishi was named its managing body the following month. At some point afterward the tree's vigor declined, which caused real concern locally. It was given treatment, and it has since been recovering.
Why a Single Tree Is Protected
Japan designates natural monuments under several criteria. This tree falls under the first, which covers notable trees, giant trees, ancient trees, trees of unusual form, and similar living landmarks. The Ohara kaya qualifies on more than one count: it is a large old tree, and it is a deformed, or more precisely an aberrant, one.
The rarity is the decisive point. The left-twisting kaya has been confirmed at only a small number of places in the entire country. Alongside Ohara, it has been recorded in Hino in Shiga Prefecture, Nabari in Mie Prefecture, and Yabu in Hyogo Prefecture. By some counts fewer than ten such trees are known nationwide. A form this scarce, occurring this far north, made the Ohara tree worth protecting in its own right.
Estimates of the tree's age vary by source. The 1942 designation record put it at roughly 150 years old at that time. Some later surveys suggest a figure closer to 250 years. The discrepancy is a reminder that dating a living tree without felling it is an approximate exercise.
What to Look For When You Visit
For most of the year, the Ohara kaya rewards a visitor with the simple pleasure of a large, well-formed conifer: dark needled foliage, a sturdy grey trunk, the calm of an old tree on a mountain slope. The defining feature, though, belongs to autumn.
When the seeds ripen, the difference becomes clear. An ordinary kaya nut is an oval about 2 to 3 centimeters long. The seeds of this tree, measured with the fleshy outer coat removed, run 3.3 to 4 centimeters in length and 1.2 to 1.6 centimeters across, roughly one and a half times the usual size. The fleshy outer layer carries five or six fine longitudinal ridges that wind gently counterclockwise from base to tip.
The twist is not absolute. On the same tree, most seeds spiral to the left, a few spiral to the right, and some barely spiral at all. That variation is itself part of what makes the tree interesting, and it is the kind of detail best appreciated with a ripe seed actually in hand. If you can, time your visit for late September or October.
It is worth knowing what kaya has meant in Japan more broadly. Its close-grained, fragrant wood is the most prized material for go and shogi boards. Its seeds, once bitter compounds are leached out, are roasted and eaten, and have sometimes been called a Japanese almond. Standing beneath the Ohara tree, a visitor is looking at an unusual chapter in a long relationship between this species and the people around it.
Planning a Visit
The tree stands in the open and can be seen at any time of year, with no admission charge. A small parking area accommodates roughly five cars. There is no ticket office and no fixed opening hours, so a visit is simply a matter of arriving.
Reaching Ohara without a car takes some planning. The nearest rail hub is Shiroishi Station on the Tohoku Main Line. From there, a Shiroishi community bus on the Ohara route serves the area, but the service runs on weekdays only and does not operate on weekends or holidays. Travelers without a car should check the timetable in advance, and many visitors find a rental car the more dependable option, especially if they want to combine the tree with other sights in the valley.
Around Ohara
Ohara is best known as a hot-spring settlement. Ohara Onsen occupies a narrow gorge along the river, and its baths make a natural pairing with a stop at the tree, particularly in cooler months.
A short distance away, near the Shichikashuku Dam, stands Zaimokuiwa, a cliff of columnar volcanic rock whose vertical joints resemble stacked timber, which is exactly what the name describes. Shiroishi also holds a second designated kaya of note, the Kotsubu-gaya, a small-seeded variety that forms an interesting counterpoint to Ohara's large-seeded one. Visitors with more time can continue to the city center, where Shiroishi Castle has been reconstructed in wood using traditional methods.
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Q&A
- When can I actually see the twisting seeds?
- The seeds ripen in autumn, so late September through October offers the best chance to see the spiraling ridges that give the tree its name. Outside that window, the tree looks much like an ordinary kaya, and the defining feature is not visible.
- Is there an entrance fee or set opening hours?
- No. The tree stands outdoors and can be viewed freely at any time of year. A small parking area for about five cars is available nearby.
- How do I get there using public transport?
- From Shiroishi Station on the Tohoku Main Line, a Shiroishi community bus on the Ohara route reaches the area, but it runs on weekdays only. Check the timetable before setting out, or consider a rental car for more flexibility.
- Why does a single tree receive national protection?
- The left-twisting kaya is a rare botanical form confirmed at only a handful of locations in Japan. A large, old example of such a scarce form, growing near the northern limit of the species, was judged worth protecting in itself.
- What else is worth seeing in the area?
- Ohara Onsen offers hot-spring baths in a river gorge, and the columnar rock formation of Zaimokuiwa lies nearby. Shiroishi also has a second designated kaya, the small-seeded Kotsubu-gaya, and the reconstructed Shiroishi Castle in the city center.
Basic Information
| Name | Hidarimaki-gaya of Ohara (Obara no Hidarimaki-gaya) |
|---|---|
| Location | Ohara, Shiroishi City, Miyagi Prefecture |
| Designation | National Natural Monument |
| Date designated | October 14, 1942 |
| Designation criterion | Notable, giant, ancient, or unusually formed trees |
| Species | Kaya, Japanese nutmeg-yew (Torreya nucifera var. macrosperma), family Taxaceae |
| Dimensions | Height about 18 m; trunk circumference about 2.05 m at chest height; root circumference about 2.75 m |
| Estimated age | About 150 years at the time of designation; later estimates suggest around 250 years |
| Managing body | Shiroishi City |
| Access | Shiroishi community bus from Shiroishi Station (Tohoku Main Line), Ohara route; weekday service only |
| Admission | Free; viewable year-round; small parking area |
References
- Agency for Cultural Affairs, Database of National Cultural Properties
- https://kunishitei.bunka.go.jp/bsys/maindetails/401/197
- Cultural Heritage Online, Agency for Cultural Affairs
- https://bunka.nii.ac.jp/heritages/detail/209510
- Miyagi Prefecture, Designated Cultural Properties: Hidarimaki-gaya of Ohara
- https://www.pref.miyagi.jp/soshiki/bunkazai/11hidari.html
- Shiroishi City, Designated Cultural Properties: Hidarimaki-gaya of Ohara
- https://www.city.shiroishi.miyagi.jp/soshiki/30/369.html
Last verified: 2026.05.23