He does

"Well... In a way I guess you could say that, yeah." He shrugged.

Yang gave him a questioning look. It seemed an explanation that simple wouldn't be enough to satisfy her.

Jaune sighed and pulled out the notebook.

"I found this... Magic notebook I guess you could say. I used it to force your mind into a trance. Basically anything I write in it becomes true. Well, within reason. So I just wrote that you would drop into a trance, go somewhere quiet with me, and I would play with you."

Yang looked at him incredulously, before crossing her arms and giving him a disbelieving look.

"You don't believe me?"

"Vom-- I mean... Jaune. Do you want "Jaune" in private..? Whatever. Look. You really expect me to buy that a magical book did this?" She sort of laughed.

"What if I prove it to you?" He asked.

Yang simply shrugged, her arms still crossed under her breasts, so the shrug made them bounce a bit... Giving him an idea.

"You asked for it" he said, as he opened the book.

"Yang Xiao-Long's breasts will grow two sizes, and her pussy will become twice as sensitive. She will notice these changes" he wrote, before looking at her. She simply shrugged again.

"And? What did you do?"

Jaune watched Yang's boobs seemingly inflate, slowly but surely. She began to adjust her shirt uncomfortably.

"Damn. Why is this shirt so tight all the sudden?"

Yang looked down. She didn't even need to take off the shirt to realize what had happened.

"W-woah!" She exclaimed. "H-how did..? Why are..?" She tried to piece everything together.

Jaune simply smiled and walked over to her.

"Believe me now?" He cooed, as he ran his hand along the inside of her thighs, brushing her clit through her shorts, causing her to shiver with pleasure.