Just in case it ever comes up, I guess, here's a quick primer on common Japanese teas:
The kind of green tea we usually drink in the US is called sencha, though it's the default tea in Japan so if you're there, they're probably just calling it ocha, or tea. If you're steeping plain green tea leaves in hot water, it's sencha. It's also generally what bottled/iced green tea is, unless otherwise specified.
Matcha, on the other hand, is a powder that's made by grinding up tea leaves. It's generally made with very high-grade tea leaves that have not been rolled before grinding. This is whisked with a little bit of hot water during tea ceremonies to create a fairly thick, strong, frothy tea. This is often consumed with sweets to offset the bitterness. Culinary-grade matcha is also often used as an ingredient in snacks, desserts, lattes, etc.
Note: not all powdered tea is matcha! There is also a type of powdery "instant" sencha as well as a cheap semi-powdered kind that's popular at quick service restaurants. I believe it's usually made from leftover/broken fragments from the sencha production process. It tastes pretty much like normal sencha, not matcha. It just has a bit less flavor than normal sencha.
Genmaicha is essentially sencha but with puffed, roasted rice in it. It looks like popcorn! It has a toastier flavor than sencha, but not a dark, tannic flavor like you get in most western teas. It tends to look a little more brownish-yellow when brewed.
Hōjicha is a roasted tea, but again, it's lighter and nuttier tasting than typical black tea. You see it a lot in the fall, and it's super cozy. Tastes and looks similar to genmaicha when brewed, but darker and stronger.
And finally, mugicha is a caffeine-free barley tea. It tastes... honestly, a little bit like corn...? Like if you just soaked popcorn in water for a while, maybe.
It's popular throughout Asia but tends to be a little less popular with tourists than the other teas. This is generally served cold, in my experience, and is supposed to be healthy for you when it's hot out.
There are way, way more kinds than this, but these are the ones you're probably going to see most often.
Personally, I usually drink iced sencha and hot genmaicha, but it's really up to your personal taste! You'll also see western-style black tea (kōcha) and oolong tea a lot in Japan, both hot and iced!