Princess Kako is not Emperor Akihito's oldest granddaughter. His oldest grandaughter is her older sister Princess Mako, age 21 who has recently been studying in Scotland and was in the news visiting with King Willam-Alexander and Queen Maxima of the Netherlands earlier this week. When she received her parure on her 20th birthday there were stunning pictures of it in the news. It is a lovely and useful tradition for Japanese Princesses.