YOU SAID:
I know im not the one that you knew back in high school
INTO JAPANESE
私はあなたが高校で知っていたものではないことを知っています
BACK INTO ENGLISH
I know you didn't know in high school
INTO JAPANESE
私はあなたが高校で知らなかったことを知っています
BACK INTO ENGLISH
I know you didn't know in high school
You should move to Japan!