Masahito Tagami spent some 900,000 yen on a relay antenna system when he opened an "izakaya" restaurant in the basement of a building in Shibuya Ward, Tokyo, last April, so that customers could use their mobile phones.
Not a cheap investment, but he said it was worth the money.
As mobile phones have become enmeshed in Japan's social fabric, a growing number of restaurant owners and landlords face the prospect of losing business because their properties -- be they either underground or up in tall buildings -- are out of reach of radio waves.