The head of a Japanese minor opposition party viewed as having extremist views apologized on Sunday for referencing a hypothetical storyline in which women have their uteruses removed after 30 as a way to deal with the country's falling birthrate.

In his YouTube channel program streamed Friday themed on declining birthrate, Naoki Hyakuta, novelist and leader of the Conservative Party of Japan, said there is a hypothetical idea, which he personally does not support, of women "having their uteruses removed when they are over 30."

"Women would not be allowed to go to universities from 18," and "a law would not allow single women over 25 to ever get married," he also said then.

In a speech in Nagoya on Sunday, Hyakuta described those remarks as too bitter and said, "I will retract them and apologize as there were people who found them unpleasant."

He also apologized for them on his X social platform the same day, saying they were "undeniably something extremely harsh" even as he had stressed during the program that the ideas were "science-fiction" and "something that should not happen."

When Kaori Arimoto, a senior member of his party joining him on the YouTube program, suggested his remarks were inappropriate, even if framed as a science-fiction storyline, Hyakuta responded, "I was explaining about the time limitation (faced by women in giving birth) in a plain way."

The Conservative Party of Japan, founded by Hyakuta in 2023, won three seats in the House of Representatives election on Oct 27 and satisfied the condition to become a national political party by securing more than 2 percent of the votes cast across all 11 proportional representation blocks.

Hyakuta has previously stirred controversy, such as by claiming that the 1937 Nanjing Massacre by Japanese troops in China never happened and characterizing U.S. forces' air raids on Japan during World War II as "genocide."