Mr. Yaun looked over Hiro who was struggling to express himself, "I think I just got what you need". He produced a jar of some ointment out of a nearby cabinet. "This will make you strong and attractive without making you stand out to much.", Mr. Yaun non-explained as he handed the jar to Hiro, "Just strip yourself and apply a thin coating of it. Do not reapply it before it has worn off completely unless you want it to be permanent. And do it when you're alone with your friend, it's more fun that way.". Hiro seemed to hesitate a bit before taking the potion, asking back, "So what is this, another muscle potion?" Yaun smiled sagely and said, "You will see" as Guy came out of the back room, now having a more reasonable amount of muscle. Guy thanked the shopkeeper and went home with Hiro.
As they arrived at Guy's place, he asked Hiro, "So what have you got?". "I'm not sure", Hiro replied, "He wanted me to try it on. Said it would wear off. Do you think I should try it?". Guy got a slight erection from listening to Hiro. He knew what the potions could do and already imagined Hiro as a muscle bod like himself, "Well I'd certainly like to see that, let's go upstairs to the bedroom.". Hiro nodded and followed Hiro upstairs.
Guy sat down on his bed, the bulge between his legs now even bigger than before as Hiro started to strip. He opened the jar and sticked his fingers into it. The substance had a silver shine to it, almost like polished chrome. He started to apply it on his skin where it seemed to leave behind a very thin film. He looked at the jar again, the only note on it said, "Apply a thin film on the whole skin. Do not re apply before effects have worn off completely. May contain traces of milk and or sugar.". He rubbed it onto his whole body from the toes to his ears as Guy watched, when suddenly he felt a tingling sensation all over his skin, "I think it's working.".
At first not much seemed to happen. The skin on his lower back started to turn black. Then his pecs started to expand and push forward. All the hair on his body disappeared revealing smooth silver new skin. The skin on his pecs started to become ridged and silver as well as it pushed forward, the ridged parts forming an X with a smooth middle part which seemed to drag the sides with it. Meanwhile his back started to become soft and a bit puffed out. He suddenly felt the urge to reach down at his member. As he touched it grew wider and longer in bursts of extasy growing in pulses until they bent to join with his neck. They looked like 2 pipes being joined by a piece of sheet metal in between. Meanwhile his breast, now a powerful engine, has expanded to meet his former member. Then his legs started to bend and stiffen. His feet bulged out and joined into a wheel. By this time Hiro already had gone down to his knees. Something similar happened to his arms and hands, forcing him to put them straight ahead as the front wheel formed. They also grew through his shoulders to form handle bars. His hairless head shrunk down in size as his face first smoothed itself out, then reappeared in the form of a lamp. During all of this his back had changed to a shiny red tank and a black leather seat. His back and bum started to grow circles of metal studs around them as leather buckles appeared on his former behinds. They formed into saddle bags as his back now seat reached its final form. Soon the rest of the bits and pieces came into place and he was indistinguishable from any red road motorcycle. Certainly much more souped up than your regular factory model, but nothing you would not expect to see on the street... less so in a bedroom.
Guy, now sporting a massive boner came to his senses, "Hiro can you hear me?" he asked the motorcycle. He looked very closely at his friend. The only obvious thing he could find was the brand name, 'Hiro' written in chrome letters on the red gas tank. There was no reply. Then something, maybe it was his curiosity, maybe some vague premonition, told him to look into the saddle bags. He first stroked over them, what just used to be his friends bum now was a pair of bags. He opened the left one and found an open helmet, something that would suit him well riding that bike. He put it on and suddenly heard a voice. "I can hear you.", cried Hiro's voice coming through loudspeakers in the helmet, "There seems to be come sort of intercom system". "Are you alright?", asked Guy. "I think I am, at least for the moment, I think I made that helmet appear in my saddlebag". Guy looked over the motorcycle and found a key in the ignition, he pulled it out, "Are you still there?", he asked his friend. "Yeah, I don't think this turned me off." Hiro started his engine and revved it up a bit before realizing that leaving an engine on in a confined space isn't a good idea. "Hey even that works" he exclaimed before he turned off his engine.
Guy looked at the key. It looked like any normal motorcycle key with one distinction. It had 2 buttons, one with the outline of a motorcycle on it. The other one with the one of a human. "Looks like I've found something." he said and pressed the human button. Suddenly Hiro started to change again, this time somewhat quicker. His wheels started to turn back into hands and feet and his front lamp started to become a head again. His changes seemed to revered rather quickly until they stopped after a few second. Hiro looked at himself. His hands already looked rather human, at a mirror he could see that his head also seems to have changed back completely. He rest of his body however was not. His pecs still showed the cooling fins of his engine and a quick rumble on his chest confirmed that he could still control it. His arms and legs were human in form, but seemingly made out of shiny metal. His bum, while now more much more formed like a normal one, still had it's buckles and one of them was still open as Hiro left it when he took out the helmet. Guy reached impossibly wide into his and pulled out another helmet for himself. Between his saddlebag bums there was his tail pipe leading to his engine, now looking like nothing more than a metallic rim around his anus. A metallic strip, the remains of his former member still held his engine in place. Maybe... with the right sort of clothing, he'd pass as a human.