You were his man assistant

Shouta was basically your 'boss'. Because you assisted him..he was a teacher in U.A. high school and he was a pro hero too. He was sometimes fed up with everything and hired you.

Shouta was grading tests, he was tired and didn't drink coffee and forgot to ask for one..maybe, if you make him his favourite one, he will realise how much useful you are for noticing his needs? You should try it.