Jennifer was not sure why Jason was suddenly bursting into laughter, but when he had calmed down, she understood it as he asked her something.
"It's quite interesting to see that you hide your identity from the cadets, while you use your disguised identity when you are in Lanro.
Is that because the Aeus and Devir race are not allowed to find you, or has this something to do with the cadets and the fact that you saved them while not being disguised?"
Only now did she understand that Jason laughed out because he had realised that Jennifer was currently in her normal, undisguised appearance, which meant that she revealed herself in front of him and the cadets.
Thus, it was only logical for him to be confused, even if she didn't really understand what made him laugh.