"Nyaha, that's a good spirit!" No, it's not. But it's funny to Shura, and it's an honest reply. Wrong, but honest.

And maybe it's just a part of this girl's personality. Of course, Shura might be seeing her bad side after startling her and teasing her. "Ah, my name? Kirigakure Shura. I guess you should tell me yours, since we're stuck together an' all~!"