Hot matcha-latte.
I'm not a matcha connoisseur, but I live north of Tokyo and have some perspective...
The commercial excitement over matcha is that it's flavor competes with coffee in cafe drinks, and chocolate in ice cream.
When you visit Japan, try out the old style of matcha long been associated with the traditional tea ceremony.
It may be hard to find this kind of matcha, but specialty shops will prepare this for you at a good price. It's delicious and is guaranteed to delight you since you enjoy traditional green tea already.
The commercially popular matcha can be found everywhere in Japan. Try a hot matcha latte served in Tully's, maybe Japan's biggest homegrown coffee cafe. I prefer adding a little sugar to the drink.
In soft serve ice cream, matcha can be found at every tourist location here. Also found in the supermarket. Yes, even Häagen-Dazs sell matcha ice cream.
Enjoy.
Hot matcha-latte.