The reason why the term for the title of shogun was changed was explained as follows: The change was made because the state of the nation in the Edo period had become stabilized, then the domestic positioning of shogun became like sovereign rather than a winner of wars, and therefore, it was intended to use the term of 'King of Japan' to clearly show that the Tokuwaga shogun became effectively a sovereign, or because the term of 'Tycoon' was used in Korea for indicating a prince, and therefore, use of 'King of Japan' was restored to remedy the unequal state of using the term.
この変更の理由としては江戸時代も安定期に向かい、将軍の国内的地位が幕初の覇者的性格から実質的に君主的性格に移行した現実を踏まえ、「国王」を称することにより徳川将軍が実質的意味において君主的性格を帯びるようになったことを鮮明にせんとしたとも、あるいは、「大君」は朝鮮国内においては王子のことを指すので、これではむしろ対等ではないので国王に戻すのだとも説明されている。