He mounts her.

Naruto then approached Tenten, and stroked her new dick. He smiled at her as she moaned and squirmed again. He then moved to mount her, guiding her new member towards his slick new pussy.

"M-Master... Or should I call you Mistress right now?" Tenten cooed.

Naruto chuckled. "Physical form aside, I'm still very much a guy Tenten, just one who can change his gender at will." He then lowered himself onto Tenten's dick, making her cry out as she felt her cock enter her first pussy.

"Master!" Tenten cried out, her length fully inserted in him. "This... It feels amazing!" she cooed.

Naruto grinned as he placed his hands on Tenten's tits, and began to grind his hips onto her. Tenten grit her teeth and clenched her fists, still not used to having a penis, let alone it being fucked.

Naruto looked down at her, and began playing with Tenten's boobs, admiring his own feminine hands on Tenten's tits. He started moving his hips up and down on Tenten's. "Oh... This feels different, and so good..." Naruto moaned, his pussy clamping down on the dick.

(For those of you still reading despite my personal kinks up to this point, I hope the gender pronouns aren't too confusing, lol.)

Tenten would have groped Naruto's tits if she wasn't tied up, but settled for bucking her hips as much as she could into her Master's female body, before crying out as her orgasm hit, and filled Naruto's pussy with her seed. Tenten panted, and Naruto also came, the sheer novelty of being able to experience pleasure from the female side enough to push him over the edge.

They panted, and Naruto said, "Heh, that was kinda fast, but the new sensations ARE pretty overwhelming..." He got off of Tenten and stretched.