serial, cereal

Serial or serial means published or broadcast in installments or in a sequence--
Years ago a weekly show  was called a serial.
His latest novel was published as a serial.
Serial may describe something else that is done or happens in a sequence--
The popular magazine styleded her varied relationships "serial monogamy".

Cereal or cereal ( rhymes with serial ) means grain, or something made of grain--
They liked to have hot cereal on winter mornings.
The cereal grasses are used for food.
Oats, wheat, rye, rice, and corn are all cereal grains.

Now that you know that, you can say--
"Their favorite box of cereal had a serial comic book printed on the back, with a new installment each week."

Note--a "serial killer" is one who commits murder multiple times--
The Boston Strangler was America's most notorious serial killer.