In addition, the word 'Kei-En' has an another meaning, a name of a school of waka poetry. (the Keien school founded by Kageki KAGAWA, who was a kajin (waka poet) in the late Edo period. Keien was Kagawa's pseudonym.)
なお、「桂園」は和歌の流派名（桂園派。江戸時代後期の歌人、香川景樹が創始した。香川の号が桂園）とも係っている。