All Japanese green tea is the same kind of tea. The differences are a matter of grade and additives. Japan's tea-making style is similar to that during China's Tang dynasty, when the Buddhist monk Eisai brought tea from China to Japan. The fresh-picked leaves are steamed thoroughly before drying, rather than withered before drying. The steaming makes the tea leaves immune to oxidation. Then the leaves are dried and rolled into shape. Heat is further applied during that drying process.
Japanese teas include: bancha, Genmaicha (tea with popped and roasted rice), hojicha (roasted tea), kukicha (twig tea), sencha, gyokuro, and matcha.
The difference is what grade of leaf that you use to create the tea. Bancha uses the largest leaves and so has a less-refined flavor. Sencha is crafted from the smaller leaves, which have a more refined taste. Gyokuro is sencha grown in the shade and thus the most subtle in flavor (reflected in the prices it commands). Matcha is powdered gyokuro whisked into water. It is what is used in the Japanese tea ceremony.
Uji, Japan, just south of Kyoto, is the most famous tea-growing region in Japan. Most of the finest teas come from this region even though it produces on 4 percent of Japan's tea.
In its bright green, unoxidized state, Japanese tea retains the natural bitterness of raw leaf. For this reason sencha needs to be steeped at a lower temperature than other green teas. Use water at 165 F to prevent the resulting brew from being overly astringent.
Sencha has a natural sweetness; it's lively on the tongue, assertive, and clean. The infusion is green, unlike how Chinese green teas appear yellow in a cup. Sencha goes very well with seafood, and its assertive taste even stands up to chocolate. Carefully store high-quality sencha in the refrigerator. Make sure there is no air in the package because moisture can build in the cooler environment. Because of its unoxidized state, you may also want to use an airtight canister for longer-term storage.