[Ah... His identity is problematic because he's...too well-known. She doesn't quite pick up on the actual nuances, or the fact that he's spying, deceiving, betraying.

What she picked up out of that was--]

O-oh...! I...think I understand a little. Saitou-san was too well-known, so everyone would know who you are... That's amazing!

[probably not quite what he meant]