Is the UK Ready for Japan's Humble Onigiri Rice Balls?

Like many tourists visiting Japan, I fell in love with onigiri, plump triangles of rice wrapped in thin sheets of roasted seaweed called nori. They were ubiquitous and cheap, less serious than sushi but still a delight to eye and palate, the perfect solution for that sudden hunger pang. So when I read that the snacks were available at branches of Marks & Spencer Group Plc and Waitrose Ltd. in London, I had to check them out.