Gradually, and very pleasurably, like Anko.

Tenten watched him put the Note away, wondering what he had written, before her eyes suddenly widened and she cried out as her hips spasmed and shot up, her limbs straining against her bindings.

She was feeling her clitoris burning, but not in a painful manner, it was a very sensual sort of heat, and every erogenous nerve in it was flaring up. She squirmed as her clit was twitching rapidly, then... It started to grow.

It began to swell, growing longer at a faster rate than it was growing wider. She bucked her hips, crying out. "What's... What's happening to me!?" she moaned out, trying to process it.

It reached four inches long, and the tip of it started forming the glans, while regular skin grew out around the length. As it reached five inches, the tip split a little, an opening appearing for semen to come out.

By this point, Tenten threatened to break free of her bindings, but Naruto made four Shadow Clones to hold her limbs down. Tenten's eyes were tightly shut as she had her teeth grit, then she screamed as she apparently orgasmed, but while her altered clitoris pulsed a bit, no semen came out, no doubt her internal testicles were still forming and had yet to connect. Unseen to either of them, Tenten's urethra shifted to connect to Tenten's cock instead of her original place to urinate from.

The process finally finished, and Tenten wheezed as the overwhelming sensations stopped. Opening her eyes, she gaped at her new body part. "Uh...Master, this is your doing right?" Naruto grinned and nodded, making Tenten nod in understanding, blushing, but easily accepting her Master changing her body for his own purposes. It was his to mold as he saw fit now, and she was happy to submit herself to it, however drastic.