Nihon-cha (Japanese tea) contains catechin (giving astringency), caffeine (giving bitterness), and tannins (giving sweetness). Tea is said to be effective in preventing colds and cancer. The tea used in the tea-ceremony is called matcha. From the sprouting of the new buds in mid-April, the whole tea field is covered so that the leaves can grow protected from direct sunlight. Owing to the protection from direct sunlight the nutrients from the roots collect in the leaves, and unique types of amino acids called tannins (which only green tea possesses) increase. You can see this kind of tea field in Yamashiro Area of southern Kyoto. Ordinary tea is called sen-cha, with the soft tips of the leaves being brewed to make tea. Aside from the ryoku-cha (green tea) mentioned above, the free tea served in some restaurants called houji-cha is made from soft stalks and hard leaves.