If you find yourself with no teapot, no strainers, and no filter, you can simply drop a good-sized pinch of tea leaves in your tea cup, then pour in boiling water. In 5 minutes you'll have a cupful of nice, brisk green tea. The tea leaves will settle on the bottle of the cup, so you won't get a mouthful of tea leaves . . . at first. As you get to the last of the tea, you will have to start practicing the art of using your mouth as a filter.
Think of this as the green-tea equivalent of "camp coffee" in terms of technology -- but not in terms of taste! Green tea brewed the way we just described doesn't taste all that different from tea brewed in a teapot, etc. Just slightly more bitter. (Whereas camp coffee, if you've ever tried it, can be an unpleasant experience indeed.) But the full-bodied (in the extreme!) taste is a nice change of pace sometimes. And just think of the boost you're getting in antioxidants and other good stuff. (And caffeine, too, so take care if you're not in the mood for too much of that.)