Mika Jinbo punches the three buttons on the slot machine in front of her, watching the reels spin as the words ''high probability'' appear on a display above.

''That means my odds for winning just increased,'' said the 41-year-old, a veteran player of 20 years, talking above the pop music blaring from her machine. ''This is how they make it hard to stop playing.''

The two-year-old game she's playing, ''Yoshimune,'' is the longest-running hit in Japan's pachislot industry, where machines are normally replaced every two to three months.

Pachislot is a fancier version of the classic slot machine. As with the one-armed bandit, the game starts when you pull a lever, but in Japan's version, you press buttons to stop the reels, adding an element of skill.

The pachinko industry - including both pachislot and the older pinball-like pachinko game - rakes in about 29 trillion yen (HK$2.02 trillion) in annual revenues from specialized gaming parlors throughout Japan, the government estimated last year.

That's nearly four times the revenue from legal casino gambling worldwide, as estimated by PricewaterhouseCoopers.

Gambling is illegal in Japan, but pachinko and pachislot are not technically considered gambling because users can only win merchandise such as food, beer, shampoo or small appliances.

Winners can exchange these items for cash at designated establishments nearby, and the goods often find their way back to the pachinko parlors.

Yano Research estimated pachislot machine sales jumped 32.5 percent in 2003 from 2002 to 525.5 billion yen.

The increase was thanks largely to two games: Daito Giken's ``Yoshimune'' and Sammy Corp's ``Hokuto no ken.''

Of the 1.8 million pachislot machines in service, 45 percent are one of those two games.

``Pachislot has become popular because it has similar characteristics as video games with the added bonus that you can win money,'' said Makoto Ishikawa, a vice manager of research at Yano, which reports annually on the industry.

``Users who were fans of video games in high school and college move on to pachislot.''

Most machines feature a video screen where animated characters hint at coming luck. ``Yoshimune'' adds shutters that open, close, tremble or reveal shadows of characters, depending on how close a player is to a big win.

A player might spend tens of thousands of yen to play for several hours.

Payoffs can reach as much as 200,000 yen.

``Hokuto'' turned a popular 1980s comic about a fighter into a pachislot game. Offering smaller but more frequent winnings, it packs in clues to let players improve through experience.

``When Hokuto starts cracking his knuckles or rips off his clothes on the LCD screen, it means something is about to happen. If you know what they mean, you have a leg up,'' said Akihiro Sasaki, a spokesman for Sammy.

``Yoshimune'' may be the longest-running game, but ``Hokuto'' is the all-time best seller. Sammy, Japan's largest pachislot maker, has sold 620,000 of them. A pachislot game is considered a hit if sales reach 20,000.

``Yoshimune'' singlehandedly propelled Daito Giken to No 5 in the industry from No 13 in 2001. The privately held company does not disclose unit sales, but analysts estimate it has sold more than 200,000 of them.

Both companies sell Sony PlayStation and mobile phone versions of their games, as well as branded merchandise ranging from cigarette lighters and action figures to instant noodles and mini refrigerators.

Daito Giken has released two ``Yoshimune'' CDs and contributes to a compilation CD of popular pachinko music.

But analysts say the gold rush may soon be over. Each pachislot machine must be taken off the market after three years. Also, regulators have curbed the amount that the machines can pay out, reducing appeal to fans who plunk down an average of 1.7 million yen a year, according to securities firm UFJ Tsubasa's estimate.

Still, Sammy is unfazed by the challenges.

``People say the pachislot business is heading into the winter season, but we disagree. There's still a lot of room to make them interesting,'' Sasaki said, vowing to hit 800,000 unit sales with a completely new machine.

REUTERS