TOKYO

NEVER tight-lipped about his recurring battle with cancer, he still surprised many Japanese by admitting that he was an alcoholic and checking himself into rehab over the summer. Family problems, he explained.

The inevitable strain of a quarter-century marriage, a cousin’s cryptic comments, existential questions about the nature of family and life itself, all of this, he said openly, had contributed to his heavier-than-usual drinking.

The family in question is none other than Japan’s imperial family, and the recovering patient is Prince Tomohito of Mikasa, a first cousin of Emperor Akihito. The family’s other members are only seen, if they are seen at all, waving at some official event. But this prince has never shied away from offering his personal opinions on everything from preserving the throne’s unbroken male line — even, he wrote mischievously two years ago, by reviving the concubine system — to the private burdens of royalty.

“It’s not only the past one or two years,” the prince said of the stress behind his alcoholism. “As long as I can remember, the imperial family’s been like one big ball of stress.”

On a recent afternoon, Prince Tomohito, 61, known as the “bearded prince” for his goatee and mustache, appeared in good spirits at his residence in the Akasaka Estate, the sprawling walled-off, wooded grounds in central Tokyo that is home to most of the imperial family’s 23 members.

A beige jacket hung loosely on the prince, still well underweight because of his various illnesses. He wore dark blue slippers that appeared to be the only concession to Japanese custom in a Western-style reception room dominated by a grand piano and chandeliers. Having studied for two years at Oxford, he sometimes sprinkled his Japanese with English words.

The prince has been in and out of the hospital since he was found to have throat cancer some 16 years ago, and last year he underwent his eighth operation for cancer. In a society where people remain reluctant to disclose their illnesses, the prince said he saw “no meaning in hiding” his cancer and even wrote a book about it.

“Our family’s DNA is highly susceptible to cancer,” the prince said. “In two generations, six of us have already been afflicted with it. So I had always wondered when my turn would come.”

Still, the prince attributed his recurring cancer to stress, the same kind of stress that, he has said publicly, first led to his overdrinking in his 30s and aggravated it in the last couple of years.

The prince, who has two daughters with his wife, Princess Nobuko, cited difficulties at home. “Things became messed up inside our home,” he said, adding, “When you’ve been together for 26 years, well, you know.”

Problems in the extended family also affected him deeply.

“There are all sorts of problems now inside the imperial family,” he said. “For example, I threw myself into the whirl surrounding the crown prince’s comments about personality denial.”

The prince was referring to an extraordinarily emotional news conference given three years ago by Crown Prince Naruhito about his wife, Princess Masako, the Harvard-educated former diplomat who has long suffered from depression and rarely appears in public. It is believed that her illness stems from the intense pressure she felt to bear a male heir to the throne — pressure that was relieved last year with the birth of a son to the crown prince’s younger brother and his wife.

“There has been a move to deny Masako’s career and personality,” the crown prince said, in comments that seemed to put an individual’s happiness on par with, if not above, the imperial family itself, comments that were endlessly scrutinized for their exact meaning and intended audience.

Prince Tomohito said he wrote the crown prince a long letter asking for further explanation.

“If he had responded,” Prince Tomohito said, “I think we could have made some progress. But there was only a reply thanking me for my invaluable opinion.”