A Japanese citrus sits at the centre of The Citrologist Sudachi Special Edition Gin, a seasonal Scottish release bottled at 42% ABV in 700ml. It is made by The Wildings Distillery in Galashiels, in the Scottish Borders, and sudachi is what separates it from the other citrus editions on the shelf.

Sudachi is a small green fruit long associated with the Tokushima region and cultivated in Japan for centuries, where it is prized in cooking. It descends from yuzu, koji and tachibana oranges, a family tree that explains both its concentrated aroma and the complexity that lingers after the swallow. Sharper and greener than lemon, it gives the gin a bright, almost herbal citrus character rather than a sweet one.

Because the fruit is seasonal, the gin appears in limited batches and then disappears until the next harvest allows another run. The distillers work with whole fresh citrus for these editions, preparing zest and juice by hand instead of relying on dried or frozen fruit, and the botanical drawings on their labels come from the artist Kate Philp. At 42% the spirit has enough weight to stay clear in a mixed drink.

Keep the glass simple: large ice cubes, a thin lime wheel and 10cl of cold Indian tonic over a 4cl pour. Lime is close enough in freshness to support the green citrus without competing through sweetness. Leave juice and syrup out of the first attempt. The aim is to keep the sudachi aroma in front and let its long citrus finish come through on its own. The Citrologist builds its whole catalogue around citrus, from London Dry and Scottish Dry bottlings to pink grapefruit, makrut lime and yuzu, and the special editions are where the rarer fruits turn up. Anyone who misses a run simply waits for the next harvest.