In which year was Emperor Akihito's eldest son's only daughter born?
Aiko, Princess Toshi Aiko, Princess Toshi (敬宮愛子内親王 , Toshi-no-miya Aiko Naishinnō , born 1 December 2001) is the only child of Crown Prince Naruhito and Crown Princess Masako of Japan.
Princess Reishi (1270–1307) Princess Reishi (姈子内親王; 5 October 1270 – 22 August 1307) was an Empress of Japan.