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紅茶キノコ (こうちゃきのこ, Kōcha kinoko) is Kombucha — a Japanese food (beverages, tea).
What is Kombucha?
Kōcha kinoko is what Westerners know under the name "kombucha". This beverage is produced by fermenting sugared tea using a symbiotic culture of bacteria and yeast commonly called a "mother" or "mushroom". Ko-cha means "black tea", kinoko means "mushroom".