YOU SAID:

I need to get a kit-kat from the store

INTO JAPANESE

店からキットカットを買う必要がある

BACK INTO ENGLISH

I need to buy kit kat from the store

INTO JAPANESE

店からキットカットを買わなければなりません

BACK INTO ENGLISH

you have to buy kit kat from the store

INTO JAPANESE

店からキットカットを買わなければなりません

BACK INTO ENGLISH

you have to buy kit kat from the store