He makes her cum by petting her.

Naruto knelt next to Sakura, stroking her back, making her jerk a little at the jolt of pleasure that made her feel, before she relaxed, raising her ass to press her back into his hand a bit better. Her purring increased in intensity as she was pet, and she began to pace on all fours, rubbing her head against his legs.

"Nyah!" she mewled upon feeling her ears erogenous sensitivity, and rubbed her head on his legs a little more vigorously. "Oh my god Master, you make me feel so good..." she purred, looking up at him longingly.

"That's the point," Naruto grinned. "I may be the Master, but you ought to enjoy yourself as well..." He then began to scratch at the base of her ears, making her mewl and purr, pressing her head against his hand.

With his other hand, he stroked at her back again, and she stretched her body up to him as much as she could without getting on her feet, her eyes closed in contentment.

Then he began to stroke her tail, making her meow again, panting and blushing heavily as her pleasure built up, quickly reaching a fever pitch. "M-Master, I think I'm gonna..." she started to say, before she mewled again as her body shuddered, having a small orgasm just from being pet.

She collapsed onto her side, purring, and smiled up at him with a whole new level of longing. He smirked as he considered how else to test her new body.