[Nana wonders, of course -- she's too much a product of a upper middle class Japanese upbringing to really miss that someone skipped their last name. Even if she's come to appreciate that different cultures handle it in ways quite unlike her own.]

Mm-hm. It is my duty. Well... maybe it's not one of the duties of the Student Council President that's spelled out. But...

[She smiles, again.] I think it's important, so I do it.