My parents have a yuzu tree in their backyard. It is not a large tree, but it is reliable — every autumn it produces more fruit than we need, small and knobby, intensely fragrant, the color of winter sunlight. We have never had to buy yuzu. It has always just been there.

On 冬至, tōji — the winter solstice, the shortest day of the year — the tradition is 柚子湯, yuzuyu: a hot bath with yuzu floating in it. The fruit goes into the water whole, or halved to release the juice, or wrapped in a small cloth bag to keep the pulp contained. The bath fills with a scent that is sharp and citrusy and clean — nothing quite like it. You feel warm from the outside in, and somehow the cold outside the bathroom feels more manageable afterward.

Why the solstice

冬至 falls around December 22nd each year — the point at which the days begin to lengthen again. In older Japanese belief, the solstice was a moment of transition and vulnerability, when the body needed extra warmth and protection to carry through the rest of winter. Yuzu, with its strong fragrance and skin-warming properties, was understood to fortify the body against the cold. The bath was both practical and symbolic: you were preparing yourself for what the season still had ahead.

The tradition has been practiced in Japan for centuries. It remains common today — public bathhouses put out yuzu on the solstice, supermarkets sell the fruit by the bagful in December, and the smell of yuzu in a warm bathroom is one of those sensory memories that stays with you.

The fruit itself

Yuzu is not eaten the way other citrus fruits are — the flesh is too sour and the seeds too plentiful to enjoy on its own. What it offers is the zest and the juice: intensely aromatic, with a flavor that sits somewhere between lemon, grapefruit, and mandarin but is unmistakably its own thing. A few drops of yuzu juice changes a dish the way nothing else can.

In our family, winter means hotpot — nabe, gathered around the table on cold evenings. The dipping sauce is yuzu juice and soy sauce, nothing more. The sharpness of the yuzu cuts through the broth and the richness of the meat. It is one of those combinations so simple and so right that you wonder why anyone would do it any other way.

Yuzu also appears in tea, in ponzu, in sweets and confections, in sake. It is a winter ingredient in the fullest sense — its season is short, its presence is particular, and it makes everything it touches more itself.

How to take a yuzu bath

If you can find yuzu — Asian grocery stores and specialty markets often carry them in winter — the process is simple. Float two or three whole fruits in a hot bath. The heat releases the fragrance from the skin gradually. For more intensity, cut one in half. For a clean bath without pulp, wrap the fruit in a small cotton