"It's difficult to imagine that Japan with an opportunity, once they pass the bill, of spending with free capital not to produce something spectacular," said Ben Collett, head of Asian equities at Sunrise Brokers. "It looks like the tide of conservative fiscal habits has turned. The chance of a phenomenal resort is high."
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He expects steel names could see a boost as "they have to build the casino out of something." He noted many steel stocks, such as Nippon Steel and JFE Holdings, haven't risen as much as the broader market in the recent rally.
Players involved in construction, including some cement and glass names, such as Asahi Glass, may see a boost as well, he said.
The obvious direct providers to the gaming industry, such as gaming machine makers Japan Cash Machine and Sega Sammy and slot-machine maker Konami, could benefit, Collett said. "It's reasonable to assume they'll see increased revenues. They're the first ones in line."
Among other companies getting a boost, Collett cites advertising player Dentsu; "new businesses will have to spend a lot," in the segment, he said.
He also expects security provider Secom will see increased interest.
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"It's kind of the same basket as the Olympics," he said. "One would assume security is going to be a big factor. Like advertising, you would see an uptick in associated businesses."
But he called Tokyo Dome a sell; "if they're going to build a convention center, Tokyo Dome is going to suffer." He expects the older facilities will lose out on business, especially against a newer competitor with a casino.
— By CNBC's Leslie Shaffer. Follow her on Twitter: