Apparently, after millennia of evolution, in the last 5 years, the Australians have discovered that making beer is much more simples than anyone had ever thought. But, in order for brew in a bag to work, you first need to get your stitcher to make a bag. We bought some lightweight white voile from Swany in Kamakura and here's the bag:
And here's the bag again in its pan, bought super cheapo in Yokohama. I made a french seam and used two circles of ribbon threaded through the casing to make it easy to pull the ends, close the bag, and hang it up to drain.
It seems you heat up the grain in the bag in the pan and then lift up the bag and let it drain. The beer tastes pretty good, and is much more flavourful than the results from brew-kits, although a bit cloudy.