The best green tea comes without tea bags. Tray loose leaves. Here's the reason why.

Green tea has many varieties

Green tea leaves comes in many variety and grades, but they all came from the same Camellia Sinensis plant. Chinese Oolong tea and black tea also come from the same plant. Japanese people use different tea for different time and occasions. Most of the green tea in Japan is steamed, some are roasted like Chinese green tea. Heat is used to suppress the leave's own enzyme to be fermented.

Green tea is also commonly called "nihon cha" Japanese tea. Recent Japanese trends "fukamushi" deep steamed style green tea, which has darker in color, and less in greeny flavor.

List of green tea leaves

gyokuro
Gyokuro
Gyokuro is the king of green tea. Tea leaves will be covered 2 weeks before picking, making the leaf contain more amino acids, which results in decreasing bitter flavor. Use lower temperature hot water (6oC) to brew tea. Strong aroma, and sweet flavor.
kabuse cha
Kabuse
Kabuse is in between Gyokuro and Sencha. Tea leaves will be covered 1 weeks before picking. Aroma is not as strong as Gyokuro, but as sweetness. Hot water (boiled water) could be used to brew. Price is higher than Sencha.
sen cha
Sencha
The most common type of green tea used in Japan. 1 bancha, 2 bancha, the early picking of new (young) leaf. Needle shaped skinny ones are thought to be better in qualities. The name came from "senjiru," brew in hot water.
matcha
Matcha
Macha tea leaf is dried after steaming, and then powdered. Matcha is used in "sado" traditional tea ceremonies. Matcha tea will be mixed to make bubbles. Matcha is used in ice cream, cookies, and sweets. Higher quality matcha has sweetness.
kona cha
Konacha
Konacah is separated powdered tea leaf while making Sencha and Gyokuro. Sushi restaurant in japan serve it as "oagari." After brewing, the tea will have vivid green color since hot water will dissolve more tea leaf.
ban cha
Bancha
Bancha is the common type of green tea used in Japan. Bancha uses low quality fall pickings. 3 bancha 4 bancha (fall pickings.) Unlike sencha, tea leaf is wholly grown, which is high in tannin, low in caffeine. Bitter in flavor.
kuki cha
Kukicha (stem tea)
Kukicha includes the stem part of the tea tree. Kukicha has more leafy flavor. Stems coming from Gyokuro and high quality Sencha is called Karigane, high end Kukicha. It contains more amino acid, which results in sweeter flavor.
houji cha
Houjicha
Lower quality tea leaves roasted to have brown color. Less in bitterness, and light easy flavor. Not considered to be a kind of a green tea, but use same tea leaves. Name Houji-cha came from "houjiru" roasting. Less in caffeine and catechin.
genmai cha
Genmaicha (brown rice tea)
Sencha or Bancha mixed with brown rice. Some brown rice is popped like a pop corn. Genmai cha has distinct roasted brown rice flavor and comforting aroma. Stronger in brown rice flavor, lower the quality.

These are variety of loose green tea leaf found on online shop