from left to right:

Princess Sayako (Princess Nori, Norinomiya), the daughter of the Emperor/Empress
Crown Princess Masako, married to Crown Prince Naruhito
Crown Prince Naruhito, the first son of the Emperor/Empress
Emperor Akihito
Empress Michiko
Prince Akishino (Prince Aya, or Ayanomiya), the second son of the Emperor/Empress
Princess Akishino (Princess Kiko), married to Prince Ayanomiya

Thanks to Jacksan1 at Thorntree