Rakushun explains about the birds and the bees in chapter 53 of Shadow of the Moon.

As noted previously, the Japanese emperor is never addressed by name (first or last) as are European royalty (e.g. Prince Charles). Posthumously, Japanese emperors are referred to by the name of their era, or nengou, not by name. The era name of Emperor Hirohito's reign (1926-1989) is Shouwa ("shining peace"), so he is now referred to as the Shouwa Emperor.

予王　[よおう]　Yo-ou, the posthumous name of the Empress Jokaku, whom Keiki served before chosing Youko.

共王　[きょうおう]　Royal Kyou
恭国　[きょうこく]　Kingdom of Kyou