YOU SAID:
Gotta keep an eye out for Selener
INTO JAPANESE
セレナーに目を光らせておかなければならない
BACK INTO ENGLISH
You have to keep an eye on Serena
INTO JAPANESE
あなたはセレナに目を光らせなければなりません
BACK INTO ENGLISH
You have to keep an eye on Serena
That didn't even make that much sense in English.