The abrupt and, at the time, inexplicable resignation of Prime Minister Shinzo Abe in September stunned the nation, prompting criticism that he was an irresponsible and immature politician who couldn’t even offer a convincing explanation as to why he quit the nation’s top post.

Abe finally confessed publicly Thursday that fear of a recurrence of a malignant bowel disease — which forced him to visit the bathroom up to 30 times a day — prompted him to give up his prime minister’s post.

Specifically, he suffers from ulcerative colitis, a chronic inflammatory bowel disease that causes pain, diarrhea and often bleeding, and can lead to other serious complications. Its causes are still unknown and pose great physical and mental burdens on the patient.

“In August, relevant figures from a blood test exceeded a normal level. (The disease) could have broken out at any time,” Abe wrote in his contribution to the latest issue of the monthly magazine Bungei Shunju, which hit bookshelves across the country Thursday.

“If it had recurred, (I) would have had to go to the bathroom 30 times a day. It would have been impossible to carry out the duties of a prime minister,” Abe wrote in his article.

Abe abruptly announced his resignation at a hastily arranged news conference on Sept. 12, saying his exit was necessary to pass an antiterrorism law in the Diet.

Abe’s doctors only explained that a “functional gastrointestinal disorder,” a set of symptoms mainly caused by mental stress, and whole-body fatigue forced him to be hospitalized on Sept. 13.

For politicians, hiding illness is considered a matter of course to continue their careers.

But Abe’s admission has also revealed the lack of crisis management of his government, as he said he almost lost his ability to make proper decisions and could not even think of asking his doctors to hospitalize him before announcing his intention to step down.

“When you can’t eat meals, you become greatly weakened and you feel so heavy as if lead was poured into your body,” Abe wrote.

“You lose spirit and your capacity to think is weakened. I might have been gradually coming to a point where it was difficult to make normal judgments,” Abe wrote.

He said the disease first broke out when he was 17, when he experienced a bloody discharge during a bowel movement.

Since then, the disease recurred once a year and each time continued for about two weeks to a month. But with recent developments of new medicines, he experienced no recurrence for several years, Abe wrote.

Then, believing he had overcome the disease, he decided to run for the prime ministership in September 2006, he wrote.

But a crushing defeat in the Upper House election last year and a series of scandals that hit his Cabinet apparently caused Abe great mental stress and raised fears of a recurrence of his disease.

With his abrupt resignation, Abe, once the political star of conservative nationalists, disappointed even his strongest supporters and led to him being widely labeled as immature and irresponsible.

But in the article, Abe, 53, insisted there is nothing wrong with his policy proposals and he is not too young when compared with other world leaders.

“What I worry about the most is that because of my resignation, the conservative principles that my administration advocated may fall out of favor,” he wrote.

He indicated he has never given up hope for his political career, saying his symptoms have become less serious and many new medicines have been developed.

“Now I, as a Diet member, would like to make sacrifices and devote all of my energy so that full-fledged conservatism will take root in Japan,” he wrote.