You do. Inflate her to J-cups.

You brazenly pull out the notebook and lay it out so hshe can see it. "See this notebook? It's magical."

"What? Magical? There's no such thing."

"Just like girls don't just grow several cup sizes overnight?" You point to the spot where you wrote her name and the H Natural next to it.

She looks down at it, runs her finger over the ink. Plain as day, the 'B' is faded black.

"That's right. I made you big in the first place. Your tits growing last night? All me."

"You did this... to me?" She glances up to you. "And you can fix it?"

"Yeah." At least you think so. You write a J next to her name. "Fixed."

"W-wait! I'm already--" She flinches and arches her back. In time with the letter turning red her breasts shake and swell. Her words fade into a moan.

You lean closer and whisper into her ear. "I would suggest cooperating. Even I don't know the limitations of this thing. For all I know, it could work like a genie. Three wishes and poof. It's done working. Or maybe it can only be used so much on one girl. For all I know, you could be stuck like you are now forever."

"R-really?"

"You sound as excited as you do scared."

The tension leaves her voice, replaced with intrigue. "W-well if what you say it true. I wouldn't be able to do anything about it. I'd have to quit the team and it's not like they could argue why." A small smile comes to her lips. "I mean... they just grew. What could I have done to prevent that?"

You quirk a brow. She's justifying it, finding a way to accept it. "You're into this, aren't you?"

She snaps out of her trance. "What? No?"

"You just said it. You don't want to be on the track team. Having giant tits gives you the excuse you've always wanted."

Sadie didn't deny it.

"They're not free you know," you say. "Convince me you deserve this."

"Convince you? You want me to... sleep with you?"

"That's a start. I was thinking a little bit more than sleeping. Of course, if you don't like it..." You put your pen to the notebook.

"Stop! Don't put me back to normal!"

"Normal?" You laugh. "I'd make you completely flat. Then you'd have no reason not to do track. Aren't I such a nice guy?"

"F-fine! I'll do it. I'll fuck you... anything. Just let me keep these. They're amazing!"

You smirk. "Good. And lets get something straight. Bad things will happen if something bad happens to me. Also, let me show you something." You offer her the pen. "Write whatever you want in there. Go on."

Confused she takes it from you and tries writing 'Diane'. It vanishes before she can finish writing it.

"Get it now? You need me. Don't try anything funny.