One of the most convenient and cheap fast food chains in Japan for Gyudon (They also have other dishes like curry). Ordering by a ticket machine is something I wish we had in the UK. It’s just brilliant!! You can get a full meal for about 500/600 Yen and the food would come to your table in a few minutes after handing your ticket/tickets in. I ordered a beef and rice set which comes with a bowl of salad, miso and hot tea!! Also opened 24 hours, even in the middle of the late night, there would always be people inside.