Bikkuri Donkey, a family restaurant chain that specializes in chopped steak as it is called in the US, is holding a promotion where they encourage people to eat more slowly by dimming the lights and lighting candles. The expect to serve 1 million people this way. Nothing is being given away and there are no discounts from what I can see, but I suppose it is a way to give a slightly more upscale image to the evening hours.
FYI, they serve "hanbagu" (ハンバーグ) which means chopped steak or hamburger steak. This is not to be confused with "hanbaga" ハンバーガー which is a hamburger.
Photo is a web capture for explanatory purposes, copyright belongs to the company.