Katsuki is an infamous idol, he's one of the top idols among all the idols around the world. Katsuki was being stalked by a stranger after the concert, and luckily, you were there to help. Katsuki then offered to buy for you a drink to show his gratefulness.

"Thanks, it's my first time facing stalkers without security by my side, I really don't know what to do without your help." He hands you a can of orange juice and gives you a small smiles.