In this Aug 7, 2019, file photo, Liberal Democratic Party lawmaker Shinjiro Koizumi, left, and TV announcer Christel Takigawa speak to the media at the prime minister's office in Tokyo. (KYODO NEWS VIA AP)

TOKYO — Japanese environment minister Shinjiro Koizumi, who has said he will take paternity leave in a rare move for a Japanese man, announced on Friday the birth of his first child: a boy. 

Koizumi, son of charismatic former prime minister Junichiro Koizumi and seen as a future leader himself, said on Wednesday he was planning to take two weeks of leave over three months, in an effort to become a role model for Japan's working fathers. 

I'll keep a priority on policy and on managing anything unexpected that comes up, while also carving out time for childcare

Shinjiro Koizumi, Japanese environment minister

But some lawmakers have criticized his interest in taking parental leave, saying he should prioritise his public duties. 

The telegenic Koizumi, popularly known as Shinjiro to distinguish him from his father, grabbed headlines in the summer of 2019 with news he was marrying Christel Takigawa, a French-Japanese television personality, and that they were expecting a child. 

Soon after, he was named environment minister. 

Koizumi told reporters he had come straight from the hospital and had been by his wife's side for the birth. 

"As a father I'm really happy that a healthy boy was safely born," a tired but happy Koizumi told a news conference. "Both of them are doing well, that's the most important thing. What a relief." 

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Japanese Prime Minister Shinzo Abe has been trying to encourage more men to take paternity leave, and for businesses to allow a better work-life balance, as part of his "Womenomics" programme of bolstering women's employment. 

While Japan's parental leave policies are among the world's most generous, providing men and women with partially paid leave of up to a year, or longer if there is no public child care, just 6% of eligible fathers take child care leave, and most of them for less than a week, according to government data. 

Koizumi acknowledged that he's heard comments both for and against his decision. "I'll keep a priority on policy and on managing anything unexpected that comes up, while also carving out time for childcare," he added. 

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"I don't really feel like a father yet, but that should come soon. I want to be a father like my dad was," he was quoted by NHK television as saying. 

Shinjiro's father divorced his mother when she was pregnant with their third son and never remarried. He told the couple when they announced their marriage that everybody "should try matrimony once."