No, it's fine. Nagi's a nice reminder every now and then, after all. As for the 'story', so to speak... I think you have it half right.

[ Random Kanji? She's got you covered though. There's a pause as she lifts the hem of her shirt just barely to show what seems to be an obscured kanji character just by her hip. Not high enough to be scandalous, just enough to show she's got one too. ]

If it's enough to bring the apocalypse, then you should probably save that for bigger ayakashi.