YOU SAID:
Peppa, what are you doing in my cereal?
INTO JAPANESE
ペッパ、私のシリアルで何をしているの?
BACK INTO ENGLISH
Peppa, what are you doing with my cereal?
INTO JAPANESE
ペッパ、私のシリアルで何をしているの?
BACK INTO ENGLISH
Peppa, what are you doing with my cereal?
That didn't even make that much sense in English.