[She was vaguely amused at fist, but now she's got Something to Prove. She smirks and turns on heel, stalking off for the river.]

Fine! Follow, will show you. You will make up for your claims I am lying. Will make sure of it.

[How ominous. Luckily the river isn't exactly far, and Oona wastes no time in plucking the scale (dark blue and a little smaller than her palm) out of her pocket and taking a seat on the shore.]

Watching? Will show you. Stupid.

[There's no magical girl transformation here or anything. She does have to take her shorts off for this though (sorry Rei, at least she's attempting to be semi-modest about it? For once??) She gets the scale wet and presses it against her thigh, sliding her hands down. With each swipe of her hands the scales appears until her legs fuse together to form the pretty mermaid tail she calls her own, slits for gills appearing at the sides of her neck along with it. The whole process takes less than a minute but at the end, while looking rather tired, Oona looks smug.

She flicks her tail proudly] See? Try to call me liar now.