On a sunny Saturday morning in eastern Tokyo, a silver Audi pulls into a parking lot and sparks pandemonium. Out of the driver's seat bounces a small, stocky man with bulging biceps, spiky orange hair, and a broad smile spread across his effulgent, spray-tanned face. He bounds onto the pavement wearing a hoodie and a T-shirt that reads SEX INSTRUCTOR. To his left, the mostly male crowd leans forward, en masse. "Shimiken!" several shout, and a clatter of smartphone shutter sounds follows like a round of applause.

"Let's go," Shimiken whispers to a handler attempting to clear a path through the throng. He raises one arm over his head to air-high-five his riveted fans. It's the morning of the Japan Adult Expo, and the crowd has been waiting for tickets. Inside, they'll get to meet the stars of their wildest fantasies. Outside, they've already caught a glimpse of something rarer: the man who has actually lived them all.

At 35 years old, Shimiken is the king of Japanese porn, more often referred to here as AV (adult video), and there is essentially nothing he won't do or hasn't done while getting busy with more than 7,500 different female costars, including a former teen pop singer, Hungarian exchange students, and a pair of 72-year-old twins. In 18 years and more than 7,000 films, Shimiken has refused only one scenario: having sex with an actress after she had sex with a dog. (He agreed to a rewrite in which the dog merely licked butter off the woman before their scene.)

Shimiken's catholic attitude toward kink, combined with what—in porn years—is an epic tenure, has earned him the widespread national recognition of a younger Ron Jeremy or a more seasoned James Deen. The 50-year-old driver picking me up from the Tokyo airport hears his name and nods: "Shimiken? Shimiken is famous. Or at least, his dick is." Everyone in the AV industry reveres both his name and his anatomy (16 centimeters—or 6.3 inches—per an online profile), though the latter is always pixelated. As Shimiken passes through the halls of the convention's backstage, robed women pop out from side rooms and coo greetings through cigarette smoke, including otsukaresama, which literally means "you must be tired." It's a standard Japanese offering of thanks, but in this case, it has an all-too-apt application. Because everyone in the know understands that Shimiken is beset by XXX exhaustion.

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A few months ago, in a fit of on-set fatigue, Shimiken went public with his feelings about the stresses of being one of the few male talents in Japanese adult video: "In this industry there are only 70 male porn stars to 10,000 women. The number of male porn stars in Japan is less than that of Bengal tigers," he wrote in a tweet. "With 4,000 new films every month, the number of male actors simply isn't enough. This industry is like a hole in the wall that needs to get bigger!" By the time he wrapped up his next money shot and checked his phone, his call to arms, or cry for help, had been retweeted more than 3,000 times.

"The 70 guys refers to the stallions on call," explains an AV filmmaker named Daeng (who requested that his last name be withheld). High-profile actors, like Shimiken, are in heavier rotation. "It's a physically demanding job, and if they do run out of juice, it's not good." The AV director Michiru Ayashiyama worries that this already overtaxed group of performers will not only tire out but also age out of relevance."I sincerely hope the younger pool increases," he says, "because soon these actors are going to get old. Their experience will go up, but their strength will go down."

And so Shimiken arrives at Japan's largest porn expo bearing a nation's libido on his shoulders. He hasn't taken a vacation in seven years. He's too busy keeping it up in order to keep an estimated $20 billion industry from going limp.