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In the bustling world of rings and chaos emeralds, Sonic the Hedgehog glided through the landscapes with his iconic blur of blue. Inside Tails' workshop, with the scent of oil and metal hanging in the air, the fox's latest invention was waiting: a machine specially designed at Sonic's request, to transform him into a female version of himself. They both held an air of excitement and anticipation, Sonic’s azure stare meeting Tails’ brighteyes as they readied themselves for the process to begin. "Are you sure about this, Sonic?" Tails asked, concern lacing his furry features. His fingers lightly drummed on the metallic surface of the machine, creating a faint clicking sound. A reaffirming nod came from Sonic. "Yeah, Tails. I've considered everything. I'm ready," he said, stepping into the machine. A hum filled the silence as Tails pressed the activation button, the soft whirring of mechanical cogs overlaying his voice as he narrated each transformational step. His hedgehog friend shivered as he felt an intense wave of sensation as the process began. "Your reproductive system," Tails started, guided by the holographic interface of the machine, "Your male external part - it's slowly retracting." "Yeah, I can feel it," Sonic responded, a drawn-out moan echoing in the room as his body rearranged itself, "It's strange but... not uncomfortable." Tails, engrossed in the data, continued, "The internal transformation has begun too. The machine is forming a womb, fallopian tubes. It's... it's fascinating, Sonic." Sonic took a deep breath, feeling his insides shift and change. The tone of his fur started to change as well, slowly becoming a lighter shade of blue. "I think..." Sonic started, a soft gasp leaving him as he looked down. His quills, once rigid and sharp, were now softening, their length reducing gradually. Also his eyelashes, once short and unnoticeable, were now starting to grow long and full. "I look like... I'm changing, Tails." Tails stopped scrolling through the interface for a moment, amazed at his friend's transformation. "Yes, you are Sonic. The color of fur, the quill shape... everything." He watched as a girl's outfit appeared, materializing right from Sonic’s own body. A blue dress and red boots. Then, he noticed the swelling on Sonic's chest, increasing slowly from A to B and finally pausing at a full C cup. "Amy's gonna be jealous, hah!" Sonic let out a surprisingly feminine giggle. His hands reached up to his chest, a soft moan letting loose as he felt the changes. "Tails, my voice...?" Sonic questioned, hearing the notable changes in pitch. "Yes Sonic," Tails nodded, reassuring his friend. "Your voice... it's more feminine now." The last change to take effect was the appearance of crystal rings on Sonic’s waist. They sparkled and shone, twirling around her. "A beautiful addition," Tails commented, slowing down the machine. Sonic stepped out, looking at her new body, her new herself, in the mirror. She felt wonderful... free. "I feel incredible, Tails. And it's all thanks to you," she said, her voice threaded with genuine gratitude. She winked at the young fox, "Ready for Sonic the Hedgegirl's new adventures?"