Rare, Japanese Goishicha Tea

Goishicha Tea – Rare Japanese Fermented Tea, from farmer Nagao Kitamura

Goishicha is a truly unique and historic tea from Ōtoyo in Kōchi Prefecture, Japan, crafted through a centuries-old two-step fermentation process that first uses aerobic fungi and then lactic-acid bacteria to transform Bancha leaves into a rich, deeply characterful tea. 

Unlike typical Japanese green teas, Goishicha’s fermentation gives it a complex, layered flavour profile: a mellow acidity, earthy savoury depth, and subtle sweet-fruit notes reminiscent of plum and dried fruit. The dry leaves are formed into small, pebble-like bricks, a traditional shape that inspired its name (“go-stone tea”).

On brewing, the liquor is clean and bright, offering a smooth, umami-rich cup with very low astringency, making it wonderfully grounding and soulful. This is a tea with real character, perfect for those who love fermented teas like Pu-erh or are curious about traditional regional styles from Japan.

At Great Tea, we feel genuinely fortunate to have sourced this remarkable Japanese dark tea. Teas like Goishicha are still largely unknown in the West, quietly preserved within their local traditions. Seeking out and sharing these rare, characterful teas is part of our ongoing journey, bringing hidden stories, time-honoured methods, and extraordinary flavours into the cup.

• Origin: Otoyo Town, Kochi Prefecture, Japan
• Tea Type: Fermented Black Tea
• Base Tea: Bancha
• Harvest Time: mid-June to July
• Producer: Nagao Kitamura

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History of Goishicha

No one can pin down exactly when Goishicha first took root in Japan, but most sources place its emergence around the 18th century. What makes it especially fascinating is how closely it echoes other tea-leaf fermentation traditions across mainland Southeast Asia and the border regions of southwestern China, for example, Myanmar’s lahpet (fermented tea leaves eaten as food) and northern Thailand’s miang.

There’s no neat paper trail proving a direct link, but the shared “ferment-the-leaves” approach has led many to suspect the know-how travelled over time through older cultural contact and trade routes, then adapted locally into the very distinctive Goishicha method we know today.

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Tasting Notes

• Aroma: warm, earthy with hints of plum and dried fruit
• Flavour: mellow umami, gentle acidity, savoury depth
• Liquor: clear, bright with soothing body

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Brewing Guide

• Tea Amount: 3g (one tea brick) per 350 ml
• Water Temperature: 100 °C (Rolling boil)*
• Steep Time: 4–5 minutes*
• Multiple infusions possible

*Note: Rather than traditional steeping, this tea is often boiled in water for 5-7 minutes, with shorter boils or steeping after, once the tea has been opened up. This gives the time for the tea to fully infuse with the water and makes a better tea liquor.

Making tips: Do not try to separate the fermented tea chunks, it will break. Just let them come apart as they boil.

Stir the Goishicha tea every minute or so to assist with the brewing - the tea can just float, so stirring does help.

It is worth straining the tea or passing it through muslin after you have boiled it for a cleaner, cleaner drink, as boiling the Goishicha tea does create a lot of debris.

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Why This Tea Is Special

• A rare fermented tea with a legacy of centuries in Kōchi, Japan
• Crafted through traditional two-stage fermentation for rich, nuanced flavour
• Smooth, savoury profile with a bright, clean liquor, excellent for mindful tea moments