A proposal to change eno-maru for tsuru-maru (the design of crane) was made before the investiture ceremony of Imperial Prince Hirohito (the Emperor Showa), but it was dismissed.
また裕仁親王（昭和天皇）立太子に先立ち、鴛鴦丸を鶴丸に代える案が生じたが、却下されている。