Between two sips of coffee, Waseda University professor James M. Vardaman comes clean to me about his decades of addiction.

"I'm hooked on that rush," he says. "The adrenaline high I get when selling a publishing idea."

Hailing from America, the acclaimed author has published five books already this year, adding to an extraordinary lineup of more than 40 Japanese and English titles. While Vardaman does not admit to having superpowers, he tells me that one secret to his productivity is remaining curious. ("I also take a lot of walks and I never forget lunch," he adds.)