YOU SAID:
I need to protect, to preserve that smile.
INTO JAPANESE
私は保護するために、その笑顔を維持する必要があります。
BACK INTO ENGLISH
You need to keep that smile, because I want to protect.
INTO JAPANESE
保護したいのでその笑顔を維持する必要があります。
BACK INTO ENGLISH
You need to keep that smile because you want to protect.
INTO JAPANESE
保護するためにその笑顔を維持する必要があります。
That didn't even make that much sense in English.