For decades nori-wrapped rice dish was mainly a snack eaten at home or in a bento, but now it has come into its own

It is barely 10am and the queue outside Onigiri Bongo already stretches around the block. Some of the 30 or so early-bird diners sit on stools, sipping green tea and poring over laminated menus. Further back it is standing-room only.

“It’s always like this,” says Yumiko Ukon, who has run this modest rice ball shop and restaurant in the Otsuka neighbourhood of Tokyo for almost half a century. “But we never run out of rice,” she adds, seated in her office near a wall clock in the shape of a rice ball with a bite taken out.