Updated 8:33 p.m. ET, 11/12/2013
(CNN) - In a private ceremony Tuesday afternoon at the State Department, Caroline Kennedy was sworn in by Secretary of State John Kerry as U.S. ambassador to Japan.
The event was closed to media, but the State Department released a photo showing a smiling Kennedy dressed in a simple black dress, her right hand raised, her left resting on what looked like a Bible held by her husband, Edwin Schlossberg. Nearby, their son John "Jack" Schlossberg looked on, wearing a dark suit, hands in pockets, his shock of dark hair an uncanny reminder of his deceased uncle, John Kennedy Jr., Caroline's brother.
The ceremony took place in Kerry's outer office. In another State Department photo, Kennedy was flanked by Kerry and Japan's Ambassador to the U.S., Kenichiro Sasae.
Sasae hosted a reception for Kennedy Tuesday evening that included a traditional tea ceremony at his Washington residence.
"As the United States rebalances towards Asia, Japan remains our most important ally," Kennedy said during remarks at the reception. She is the United States' first female ambassador to Japan.
Kerry also attended the evening event and called Kennedy a "superb new ambassador."
"In many ways, she's been an ambassador all her life," Kerry said.
Kerry recalled that he first met Kennedy when she was just 4 years old, while working with her uncle Ted Kennedy. In that encounter, he said, he accidentally stepped on her toe, causing Kennedy to burst into tears.
"I know how proud Uncle Teddy would be if he were here," Kerry said.
Kennedy, 55, is a lawyer by education, the author of 10 books and a mother of three. She has little diplomatic or government experience, but her connection to President Barack Obama - she was the national co-chairwoman of his 2012 campaign - and her family legacy could be a plus for the U.S.-Japanese relationship.
"Japan, Mr. Ambassador, knows that it is getting an envoy who has the ear of the President, the respect of the President and the affection of the President," Kerry said at the reception.
Kennedy's swearing-in came just 10 days before the 50th anniversary of the assassination of her father, President John F. Kennedy.
- CNN's Brian Rokus contributed to this report.