On a recent weekday morning there was little to suggest that Yumeshima – “Dream Island” – could, by the end of the decade, be the site of an unprecedented experiment with gambling in the world’s third biggest economy.

A stream of trucks disappear into an undersea tunnel taking them to the island, while boats laden with soil plough the strip of water separating it from the mainland. From a distance, Yumeshima looks more like a sprawling building site than the possible location for Japan’s answer to Macau or Las Vegas.

Six years after the government legalised casino development, Osaka is vying with nearby Wakayama and the central city of Nagoya to open Japan’s first “integrated resort” – a ¥1tn (£6bn) complex of hotels, conference and entertainment facilities, with a casino as its money-spinning centrepiece.

The western Japanese city is now considered the frontrunner after the local assembly, where the rightwing populist Osaka Ishin no Kai is the strongest party, recently approved a bid that will be sent to the central government by the 28 April deadline.

The envisaged resort will “be an engine of sustainable economic growth for Osaka and the region,” Osaka’s mayor, Ichiro Matsui, told assembly members.

He has an ally in the prime minister, Fumio Kishida, who said integrated resorts were the “key to Japan’s efforts to become a leading tourism nation” when it finally reopens to overseas visitors locked out during the coronavirus pandemic.

But despite campaigning in local elections on a pro-casino platform, Matsui and his allies are facing a backlash from citizens’ groups concerned about the cost of developing Yumeshima, which was built on reclaimed land during the boom years of the 1970s, and the casino’s potential to become a magnet for organised crime and gambling addiction.