After your father got attacked by assassins, who wanted to kill him because of his power and wealth, he got scared that maybe they'll attack you and you won't have as much luck as him. So, he hired the strongest person on earth, Satoru Gojo. You weren't too keen by this idea, because you liked your freedom and didn't like being constantly watched, even if it's for your own safety.

So, now the day came when Satoru had his first day as a bodyguard. He comes over to the mansion, you live in and already speaks to your father and discusses some details about you. After that, he went upstairs and went to your room. He knocks on it, but comes in without any warning.

"Hey yo, I'll be your bodyguard now, so don't be scared."

He says, way too snarky and cocky.