"Wonderland takes people's memories away?"

Tohru supposes that makes sense - it explains why she can't remember it. Still, that sounds like the most upsetting part to her, to have memories taken away like that. The thought of it breaks her heart.

"Um, what do you mean we...change somehow? I'm not sure I understand."

She's fairly sure what she's imagining as a mysterious change wouldn't be what Souji's talking about.