Black Koji Heicha

This rare koji-fermented tea comes from the island of Tanegashima in southern Japan and is produced in the Heicha style—Japan’s own interpretation of post-fermented teas. The defining step in its creation is the use of black koji (Aspergillus luchuensis), a traditional fermentation culture famed in sake, miso, and soy sauce making. Applied to tea, koji works gently on the leaves, breaking down components and creating naturally occurring acids and complex flavors during a slow maturation process.

This black version offers a more powerful and intense aroma than its white counterpart, with a fragrance both rich and intriguing. On the palate, the difference is surprisingly more subtle: both are marked by a mild, unique acidity reminiscent of aged Bancha, yet the black has a slightly deeper undertone and more body.

Expect a liquor of amber depth, smooth and slightly tangy without any harshness. The koji fermentation imparts not only acidity but also a rounded texture, making each cup warming and satisfying. It’s a tea for curiosity-seekers and lovers of traditional Japanese fermentation alike.

For comparison, see the White Koji Heicha and explore how the shift in leaf processing changes primarily the aromatic profile rather than the flavor structure.