I recently purchased some Sencha Karigane (see review) and had a hunch that it might make good iced tea. The temperature and humidity spiked recently here in NYC, so I decided to give it a shot.
For my first attempt, I used my Hohryu (see review) to brew 12g of karigane in 300ml of hot water; I brewed three infusions according to Hibiki-an's guidelines and just added them all to my iced tea pitcher (see review) which I then placed in the refrigerator to chill. The resulting tea was quite robust with a karigane "bite" and a refreshing bitter sweetness; in retrospect, I think adding 100cc's of water would have benefited the final product.
My second experiment involved cold-brewing the same amount of karigane in a liter of water in the refrigerator for about five hours. This batch was vegetal, non-bitter, and particularly refreshing because it had a salty tanginess that seemed to replenish my flagging electrolyte levels.
Both methods produced results that tasted very different not only from each other, but from traditionally brewed Sencha Karigane as well. I recommend trying both to determine your preference--if you love Japanese green tea and are an iced tea drinker, you owe it to yourself to give this a try.