A small, soft "...Eh?" escapes his throat.

That raises so many questions, none of which he wants to ask for fear of upsetting Kaworu. Ironically, some of them might even fulfill Kaworu's wish to be more familiar with him. Midoriya can feel his own shoulders tense. He clears his throat.

"Did... um... Did you go to school?"

Going to school isn't necessarily a sign of a happy childhood, but he's got to start somewhere.