Princess Mako, the eldest grandchild of Japan's Emperor Akihito, 83, and Empress Michiko, 82, will soon become engaged to her university classmate and is expected to marry early next year (2018), news reports revealed this week.
Princess Mako is the daughter of Prince Akishino, 51, the emperor's second son, and his wife Princess Kiko, 50. She has two siblings: Princess Kako and Prince Hisahito.
In line with Japanese Imperial household law, she will lose her royal status after marrying a commoner. This has reignited debate on the ever- shrinking royal family and the monarchy's male-only succession.
Here are some things to know about Emperor Akihito's four grandchildren:
The 25-year-old princess is expected to marry law firm employee Kei Komuro, also 25, in early 2018.
The couple met in 2012 while they were both studying at the International Christian University in Tokyo.
Princess Mako enrolled at International Christian University in April 2010 - the first Imperial family member to attend it - where she majored in arts and cultural property studies.
She also spent nine months as an exchange student at the University of Edinburgh in Scotland.
After graduating, she went on to study at the University of Leicester in England, graduating in January 2016 with a master's degree in art museum and gallery studies.
She is now an affiliate researcher at the University Museum at the University of Tokyo, and and is also pursuing a doctoral programme at International Christian University.
The princess, who enjoys reading and drawing, has served as an honorary president of events like the Tokyo International Book Fair as part of her official duties.
Mr Komuro also studies at Hitotsubashi University's Graduate School of International Corporate Strategy, majoring in business law. He has not yet qualified as a lawyer, Japan Times reported.
Following in the footsteps of her elder sister, Princess Kako enrolled in Tokyo's International Christian University in April 2015 after quitting Gakushuin University.
The 22-year-old will be an exchange student at the University of Leeds from September 2017 to June 2018, the Imperial Household Agency said in April 2017.
It added that the princess had not yet decided what she wanted to study, but had shown interest in psychology and art.
Ten-year-old Prince Hisahito, whose name means "serene and virtuous", is Emperor Akihito's only grandson.
He enrolled in Ochanomizu University Elementary School in 2013, breaking the tradition of royal princes attending Gakushuin Primary School.
The adorable and photogenic prince has already gained many fans on social media.
He is third in line to the throne, after his uncle Crown Prince Naruhito and his father Prince Akishino.
The only child of Crown Prince Naruhito, 57, and Crown Princess Masako, 53, entered high school in 2017, after graduating from Gakushuin Girls' Junior High School in March 2017.
The 15-year-old, known as the princess who never smiles, missed at least a month of school in 2016 due to an unidentified medical complaint.
She was also unable to attend school for a period in 2010 as a result of the "rough behaviour" of some boys at school.
Her mother Princess Masako has battled issues of her own. After her daughter was born, she started having panic attacks and was said to be depressed in 2002. Her public appearances have been few and far between.
Princess Aiko's birth sparked debate in Japan over whether the the Imperial Household Act of 1947 should be changed to allow women to inherit the throne.
However, proposals for reform were put on hold after her cousin Hisahito was born.
SOURCES: THE JAPAN TIMES, CHINA DAILY, SOUTH CHINA MORNING POST