YOU SAID:

I will kill the monster that beheaded my father

INTO JAPANESE

私は私の父を首にしたモンスターを殺す

BACK INTO ENGLISH

I kill the monster that has fired my father

INTO JAPANESE

父を解雇したモンスターを殺す

BACK INTO ENGLISH

Kill the monster who fired his father

INTO JAPANESE

父親を解雇したモンスターを倒す

BACK INTO ENGLISH

Kill the monster who fired his father