YOU SAID:
Genji Shimada and Hanzo Shimada are mortal enemies and brothers.
INTO JAPANESE
源氏の島田と半蔵の島田が不倶戴天の敵と兄弟です。
BACK INTO ENGLISH
Shimada of the tale of Genji and Hanzo Shimada is a mortal enemy and brother.
INTO JAPANESE
源氏物語の島田と半蔵の島田は、不倶戴天の敵と兄弟です。
it is unlikely that this phrase will ever reach equilibrium