The traditional staple is losing the battle with more convenient and cheaper alternative foods

The Dojima branch of Yoshinoya in Osaka is doing a roaring lunchtime trade. As soon as one diner vacates their counter seat, another takes their place, while staff take just seconds to assemble the next order of the restaurant’s trademark dish: gyūdon.

The Observer has joined the rush, ordering a set lunch of seasoned beef and onion on rice, and side dishes of pickled cabbage and miso soup – all for a extremely affordable ¥632 (£3.46).