Hermione awoke, she had been dreaming about Harry and Ginny, as she did most nights. A wild fantasy she knew would never be fulfilled. Pictures of the two of her best friends going at each other, Ginny stood in full view being thoroughly fucked from behind. Her desperate moans echoed through Hermione's mind - Harry's deep grunts as thick white cum spilled out of Ginny's pussy. It was still pitch-dark outside, and Ginny was curled up on her side facing away, still topless, still fast asleep. Until then she had only ever touched herself fully clothed, needing to feel the safety of her underwear, but now a switched had been thrown in her sexually-repressed brain and she realised that the thought of getting caught was incredibly exciting. Deciding she wanted to try getting a little more naked, she lifted her hips off the bed and very carefully pulled her pyjamas and undies down to her ankles. Still under the duvet, she spread her knees to a diamond shape, and lightly fingered along her hairy slit. Already self-lubricated from her erotic dream, she sank back into the pillow and touched her clit more deliberately. Using an open-palm, three-fingered technique she had learned from her book, she rubbed herself in wide, firm circles. She closed her eyes and went back into her dream, imagining the gorgeous girl sleeping next to her being held upright and ploughed from behind by Harry's huge, throbbing cock - glistening from her juices. Again and again, dream Ginny came like this, the sensation of being stretched sending her over the edge, her insincere begs for mercy sending Hermione crazy. Faster and faster Hermione rubbed, by now dripping onto the bed sheets, sure she was going to wake her friend. Orgasm washed over her, her hips and legs quivering as she rode out the climax, imagining being pumped full of cum until it leaked out of her. Slowing her rubs to a stop, she let go of the breath she had been holding and looked next to her. Still asleep - thankfully. She closed her eyes, relishing the satisfaction and relief - the freedom of having her pussy out. She'd never felt so dirty, and she loved it!

Slowly rising the next morning, Hermione felt something wrong. Shivering, she looked down and with an absolute horror, saw her pyjamas around her ankles and the duvet at the bottom of the bed; she was on full display!

"Morning, 'mione!" Ginny was awake! And she was sat staring at Hermione's body, reading her book! Mortified, Hermione wasn't sure what to do or say.

"Um... hi..."

An incredibly awkward silence passed between the two girls, as Ginny looked at Hermione and Hermione tried to avoid eye contact, turning red in the face.

"So..."

"I don't want to talk about it."

"Sure..."

"It's really embarrassing." Hermione used her wand to clean up, and pulled her pants back on.

"It was kinda hot to wake up to."

"Stop it! I shouldn't have done it, I just... enjoy it... a lot. And I think and dream about it all the time and sometimes I just... need it."

"I understand, 'mione. But I worry about you being addicted. How often do you masturbate?"

"That's none of your business!"

"I'm serious, tell me!"

"Once before bed, once when I wake up, sometimes during the night. And maybe another once or twice in bathrooms during the day."

"That's... insane."

"I thought masturbation was normal?"

"I don't think that much..."

"Oh... but it feels really good!"

"I know, I do it too!"

An idea popped into Ginny's head.

"You know, there's lots of complicated charms in here, for pleasure, transfiguration, all kinds of things. Maybe I should put a chastity spell on you?"

"What does that mean?"

"It means you wouldn't be able to touch yourself, only other people would."

"Er... but... I like touching myself. And who else would do it?"

"I would. We're young, neither of us know much about this stuff, and I think this would be a fun way to encourage... exploration."

"Um... okay, I guess? But you'll take off the spell if I want? And you'll touch me?"

"Of course."

"Okay."

Ginny took her wand from the nightstand, pointed it at Hermione's midriff, and muttered an incantation. Immediately a warm feeling stretched around Hermione's private area, like she'd put on another ten pairs of underwear. The feeling dissipated, and she was left as before.

"I guess... see if it worked?"

Hermione took a hand and tried rubbing herself through her pyjamas. Her hand got a millimetre away before it stopped. She pushed as hard as her arm would allow, but an invisible force-field was preventing contact.

"I can't..."

"Good! Now I think we should go for breakfast?"

"Or we could stay here...?" Hermione pulled herself up to rest her head on Ginny's shoulder, placing an arm around her.

"If you wait until you are really really desperate, and work yourself up slowly it feels so much better."

"I am desperate!"

"No, you're a bit horny. It'll be better if you wait. Come on, I'm getting hungry."

They put their dressing gowns on and headed down to the kitchen where Mrs Weasley was preparing sausages and eggs, and Harry was sat reading today's Daily Prophet.

"Good morning, girls! Did you sleep well? Breakfast will be two minutes, oh, where's Ron? Harry dear, where's Ron?"

"I can..." Harry began.

"No, no. You stay right there, I'll go fetch him. He could sleep for England, that boy. I don't know what's wrong with him!"

Mrs Weasley left the room in her usual flap. Hermione sat down next to Harry, Ginny opposite them. As soon as Hermione's butt hit the seat, she felt an slight tingling sensation... down there. Blushing slightly, she adjusted her posture, but it didn't stop. She glanced across at Ginny, who was wearing a sly, naughty expression on her face. She was toying with her! Harry started talking to them about some story he was reading, but the two girls weren't paying attention. The tingling was gradually increasing in intensity, and it was taking all the Hermione had not to react. Mrs Weasley returned with a groggy-looking Ron, and soon Bill and Fleur, and Mr Weasley had joined them. The tingling continued, causing Hermione to go slightly pink in the face and tense her legs and stomach. It was a sensation she had never felt before, her entire clit seemed to be sending signals to her brain all at once - and yet there was nothing touching her apart from her underwear. She knew it was Ginny; she'd have read some spell in the book and was teasing her. She became worried that she was going to orgasm right there in front of everyone, and they would all see what a disgusting, dirty girl she was. But as the tingling continued over breakfast, she never climaxed. She got impossibly close, but then the sensation would back off or stop entirely until she had calmed down - then it would start slowly building again. She lost count of how many times she nearly disgraced herself; breakfast seemed to go on and on. The anticipation, knowing there was nothing she could do about it. Knowing that even after breakfast she couldn't hurry off to relieve herself; that Ginny was going to keep this going all day. Listening to Mr Weasley talk about all the raids his team was doing, to Ron and Harry eagerly joining in and pointing out how unimaginably evil the Malfoys are was usually fascinating, but Hermione was focussed entirely on Ginny and the mounting pressure and wetness between her legs. Little did Hermione know, Ginny was also hiding her arousal. The sight of her friend squirming in full view of everyone, the thought of what she must be feeling was making the young Weasley girl increasingly horny. Her refusal to wear underwear meant her juices were leaking directly down her legs. Crossing her legs under the table just meant her pyjama bottoms got messy, which turned her on even more. She imagined the mess Hermione must be making down there, her thick slime covering her from front to back, leaving a damp patch maybe all the way through to her trousers.

Eventually, after twenty painful minutes, Mrs Weasley announced that everyone should get dressed as they'd be going to Diagon Alley to buy school supplies. Hermione shot upstairs, closely followed by Ginny.

"What the hell was that?"

"Edging charm. Did you enjoy it?"

"No I didn't enjoy it! I nearly embarrassed myself in front of everyone!"

Ginny began to undress, revealing her perky little tits and her obviously wet snatch. She stood fully nude in front of Hermione for a moment, allowing her friend to take her in.

"You were never going to! You can't, that's the point. It's an edging charm - it's gets you as close as you can get but doesn't allow you to… you know. You have read that book, right?"

"Yeah, but I had no idea what edging was. Why would you do that? Deliberately not…"

"It builds the desperation, like I was talking about earlier. I do this to myself all the time. Come on, get dressed!"

She found some jeans, making sure Hermione knew she was not planning on wearing underwear again.

"Can't you… touch me? Please?"

"Of course not, don't be disgusting!"

"Oh… I'm sorry, I thought… after last night…?"

"I'm joking, silly. But they will be waiting for us downstairs. So chop chop!" She slapped Hermione's butt, and briefly rubbed her wet cunt for a second - eliciting a pained, desperate noise - before turning around and walking out of the door, leaving a deprived Hermione to desperately try in vain to touch herself.