Japanese green tea is one of the best drinks medically endorsed by practitioners world-wide. It happens to be my personal favorite - as it packs in 0 fats, 0 sodium, and 0 sugar.
My favourite brand continues to be. 'TA-Fu koshun-en', which is an authentic Japanese - for being grown & processed natively in Japan, and here is the best part.. each tea-bag is packaged individually in a foil pack. (It doesn't get any fresher than that.)
In the F & B arena, both Sakae Sushi & Sushi Teh offer different variety and flavour. I personally find the brown-rice flavoured green tea at Sakae Sushi a bit strong.
The origins of green-tea date back from the times when monks used it to maintain concentration, without indulging in funky foods. Also, unlike the imperialist British culture of drinking tea (or coffee) with milk and sugar (eewww) - green tea does not leave you bloated and does not cause a sudden spike in energy levels. (A sudden sugar-rush from traditional drinks is bound to leave you in a slump after it subsides, and gets you craving for more sugar.)
Try it for a week to appreciate it.