Rin hurried eagerly down the hallway, barely able to conceal his excitement at the package he clutched in his right hand. His tail wagging side to side eagerly, he made his way into his room, shutting and locking the door behind him despite Yukio's not being there. Once he'd done so, he tore the packaging off the item to reveal a bright blue, translucent, flashlight-like object with runes inscribed down its length, leading to the soft, squishy entrance. Grinning to himself, Rin began to strip off his clothing, slipping his pants and boxers over his already-erect cock, painting them with streaks of semen. He reached down and stroked his member a bit, smearing the pre-cum from his tip across his entire shaft, lubricating all six inches of his teenage demon length. His fingers brushed his exposed cock head and he moaned a bit in pleasure.
Without further ado, Rin aimed his cock with one hand and brought the rune-inscribed fleshlight down onto his erection. Immediately, he felt a fire building in his nether regions as the masturbator, slick with his pre-cum, slid effortlessly and smoothly up and down his length, meeting his crotch with a satisfying squelch with each pump of his hand. Drool spilling down his chin from the sheer pleasure, Rin knew nothing but the wet, squishy sensation around his length, and he wanted more. He began thrusting his hips forwards as he gripped the fleshlight with both hands, slamming it onto himself with even greater force,
Harder and faster he thrusted and pumped, until suddenly he went deeper into the fleshlight than he had gone before. He found his cock trapped inside the warm, jelly-like substance that filled the interior of the masturbator. It felt as though the fleshlight was clamping down on his length, holding his cock in place. He groaned aloud, panting as the pressure on his cock grew and grew. He looked down and gasped at the suddenly foot-long and very thick snake that extended from just above his balls.
"Ah...f-fuck!" Rin cursed to himself as the fleshlight crushed his aching cock, constricting it tighter and tighter like a boa constrictor wrapping around its prey for the kill. But almost as soon as the pain had started, it all vanished, accompanied by the sound of glass shattering and a cry of pleasure as Rin came. Hot, white sperm splashed across the walls, the floor, and Rin's desk. More importantly, the homework on his desk. As his cock pulsed the last few times, squirting the remainder of his seed, Rin let out a moan of relief, panting as he caught his breath. But something felt off. A little off than before he'd noticed his cock getting bigger. Rin looked down and laid his eyes upon the largest dick he'd ever seen, hanging between his own two legs. It was almost as thick as his arm and maybe even longer. He stared in awe at the sperm-splattered tree trunk of a manhood he now possessed.