[The question makes her pause for a moment; it's a weird thing for a boyfriend to ask, right? But she continues answering to the best of her ability.]

I was in high school, 16—no it was 15. I wasn't dating Kaito yet.

[It feels awkward to bring up past boyfriends, but that should answer his second question. It's hard for Misa to remember a time when boys didn't matter.]

Your birthday is coming up, isn't it?