BODY SWAP LABORATORY (Pixiv Fanbox)

“Heihachiro, we have the same result again～. What do you think of this?”

　Norio Makita grumbled bitterly, resting his cheek on his hand. They are in the middle of an important research project, but his face, which could be described as handsome, was completely relaxed. Heihachiro Okura, who was approached by Norio, gazed at the scene of two laboratory mice in a cage mating while they made noises to each other.

　Heihachiro wrote down the same content as usual on his tablet for what seemed like the umpteenth time, and then scratched his temples with the head of his pen.

＊＊＊

【BODY SWAP LABORATORY】

　Eisai University is one of the top universities in Japan. In a room in the research building, Heihachiro and his colleagues are conducting research using mice. AI and other technologies continue to develop by leaps and bounds. Amid such a situation, they are devoted to an occult-like research project in which the minds of two organisms are swapped, which is often looked at coldly by the people around them. Even so, they never stopped their research.

“Norio, haa…… Don't make me say the same thing over and over again.”

　Tired of watching the odd behavior of the mice himself, Heihachiro leaned back against the backrest and chided Norio, who showed no signs of tension. To be honest, though, the research with mice alone was believed to have plateaued.

　They subjected two mice to special stimuli and observed them while measuring their brain waves. After a short time, the brain waves of the violently convulsing mice showed opposite patterns, as if they had been swapped. From this experiment, it was surmised that the two mice's bodies had swapped. But that was soon to be a dead end.

　Needless to say, the mating between mice of the same sex that they are now seeing is the cause of the problem. Oddly enough, after mating, the brain waves of the two mice returned to the same pattern as before. This suggests that even if the two mice's bodies had swapped, it was only temporary, and that they would return to their original state after mating.

(It could be considered natural for them to try to return to their previous bodies once their spirits have been swapped. That may be what led the males to mate…… Then, having mated, their spirits have returned to the original bodies. Or it is possible that the experience of intense stimulation caused the body and spirit to fuse, and the two bodies completely 【swapped】……)

　Although Heihachiro has hypothesized to that extent, this is only speculation, not truth. That does not mean that he has the means to take his research to the next level. For now, it is safe to assume that no further progress will be made. He scratched his head with a sigh and casually looked at the mice in a state of post-nut clarity after ejaculation. At that moment, another researcher appeared in the laboratory.

“Hey, hey, Natsuhiko! Even though this lab is in a deadlock, you can't let an outsider in here.”

　Natsuhiko Hirakawa, the man who opened the door with a rusty sound, stepped into the room with a smile on his stern face, despite the professor, Heihachiro, pointing so out to him.

　Eisai University is well known for its philosophy of 'both the literary and military arts' and for owning a number of sports teams. As such, the on-campus facilities include a heated swimming pool, tennis courts, and indoor practice fields for baseball and soccer, not to mention a training room. The men who work hard on their research at the university are naturally proud of their bodies. For example, Heihachiro is from the rugby club and Norio is from the swimming club.

　And Natsuhiko is over 190 cm tall and has such an imposing physique that he was selected as a judo enhancement athlete in the open weight class. The man who appeared behind him in a flash was Akira Kawai, a researcher in the brain science lab next door.

　Although he is only in his 20s, he has obtained numerous patents and is popular among female students at Eisai University because of his handsome face. His beautiful appearance has sometimes led to whispered and unfounded rumors that he may be having an affair with a man.

“I'm sorry, Professor. This guy was really insistent on seeing this lab. You too know Akira──, Kawai, don't you? He's just so smart──”

　With those last words, he fell to the ground. His large body convulsing from the needle that had been thrust into his neck and he rolled his eyes back. Then the sound of the laboratory door closing and locking echoed through the room. Akira's sudden action naturally left both Heihachiro and Norio unable to comprehend what had happened, and they were stunned, their gazes focused on Natsuhiko lying on the floor.

“Hey, Natsuhiko! Are you okay!?”

　Perhaps reacting to Heihachiro's call, Natsuhiko's body jerked. Although Heihachiro was relieved that Natsuhiko's life seemed to be in good condition, he could not help but wonder about Akira's actions. The answer, however, soon became clear.

“Sorry for getting you involved, Professor Okura, and Mr. Makita.”

　Akira, with a smile honoring his beautiful neutral face, kicked Natsuhiko's torso as he slept through snore like a rumbling of the ground and bowed reverently. The gesture was so sexy that even two people of the same sex could not help but admire it.

“So……, why did you come to this lab?”

　Heihachiro asked Akira, who was stroking Natsuhiko's huge body with a suspicious hand. But he didn't answer the question. Instead, he flashed his newly acquired needle at them as if to threaten them, and then he put both Heihachiro's and Norio's arms behind their backs and restrained them with zip ties.

“What are you going to do!?”

“Don't be so alarmed. I don't intend any 【harm】 to you guys.……”

　With a hint of unconcealed brightness in his voice, Akira lightly fingered the keyboard and entered a command into the system to activate the same 【Body Swap】 function that Heihachiro and the others had used on their mice. Then he hit the enter key, and an eerie aura instantly covered the entire lab, and a feeling of discomfort swept over Heihachiro and Norio as if it were clinging to their entire bodies.

“No way, it's ……!!”

　Akira nodded with a grin and a sticky smile as Heihachiro raised his voice, having a bad premonition.

“It will happen exactly as you have imagined.”

　The vision of everyone in the room instantly became distorted, and they felt as if their bodies were being pulled in the direction of a nearby figure, and at the same time, their consciousness was suddenly cut off.

＊

“……What, what happened?”

　Norio woke up and moaned in a low voice. The moment the 【Body Swap】 function was activated, a horrifying, hair-raising sensation ran through his body. Although he had physically regained consciousness soon after passing out, alarm bells were still ringing in the back of his mind that something bad had happened. Norio looked into the face of Heihachiro, who collapsed beside him, and was speechless. Then he realized. He was no longer 【himself】──.

“Nn……? Ugh? Norio……, are you okay?”

　Despite him, Heihachiro blinked his eyes and raised his upper body. In the blurred vision, a moving figure is reflected. He was relieved to see that neither of them seemed to be in life-threatening condition, but he soon realized that this was not the time to be so carefree.

“Am I there?! If the 【Body Swap】 has succeeded?!”

　Heihachiro, who had taken the form of Norio, raised a high-pitched voice, and Norio, who had taken the form of Heihachiro, raised his head up and down to show his approval. Heihachiro wanted to express his joy at the fulfillment of his long-cherished wish, but he was too stunned to speak. They checked each other's expressions, but the presence of their own familiar faces made it even more difficult for them to hide their confusion. Then, something happened that made them feel even more confused.

“Ugh……!!”

　A neutral moaning voice makes them look in that direction, and they see that 【Akira】 has just awakened. Shaking his head fully to awaken his consciousness, he realized that he was sitting on something soft, and turned his eyes in that direction. He then opened his eyes in surprise.

“Huh?! Me……, there's another me?!”

　While distorting his beautiful face with an impudent expression, 【Akira】 raised an inverted voice. It's not unreasonable. He had just awakened to find a man lying in front of him who looked just like his former self. Then, as if taking that voice as a cue, 【Natsuhiko Hirakawa】, who had been pinned under him, regained consciousness and stood up his huge body.

“Ah……, yes, that's right. My name is Natsuhiko Hirakawa.”

　He said in a sweet tone of voice, and then he quickly turned around behind 【Akira】 and squeezed his carotid artery, causing him to fall into a stupor. Then, he looked surprised for a moment at his own fluid movements, but immediately looked around at his own body with a satisfied smile on his face. Arms as thick as logs, knobby, burly fingers. Thick, voluptuous breast plate. As he took in each part of his body, his nostrils flared and he was breathing heavily.

“Hah, hahhh♥♥ Too sexy body…… Oh my goodness♥♥ I've always wanted to have this erotic body♥♥♥”

　His voice leaked out of his mouth as if he were a dirty old man. He stroked his muscular, sweat-soaked body with his hands, and then he ran his fingers over his own hard, erect manhood. He turned his body upside down and turned his vacant eyes to the ceiling. His brain must have been producing a lot of pleasure chemicals. He immediately rolled his eyes back with drool and snot running down his nose. Then he hugged his own body tightly as if he were holding his beloved. And, he inhaled his chest full of sweaty body odor and took several deep breaths, building up his arousal.

　After he licked his lips and muttered, he took several things like a patch out the pocket of 【Akira】's lab coat, and applied them to his own temples and the ball sack of the partner in front of him.

　Then, 【Natsuhiko】 forcefully opened the crotch of 【Akira】, who was lying on his face on the floor, and rubbed 【Natsuhiko】's warped rod around 【Akira】's closed anus. Every time the tip of 【Natsuhiko】's cock, wet with pre-cum, touches the hole, 【Akira】's lower mouth wriggles hungrily, opening and closing repeatedly. When 【Natsuhiko】's mouth relaxed at the sight of that, he forcefully screwed his cock into 【Akira】's anus and began to violate his asshole deep inside. The obscene sound of gurgling water reached the ears of Heihachiro and Norio. Immediately thereafter, the sound of busy muscles colliding with muscles filled the room.

“Oh♥ OHHH♥♥♥”

　【Natsuhiko】 was moaning wildly and shaking his hips wholeheartedly. Facing such a scene, Heihachiro and Norio were speechless. But it was not out of surprise. Natsuhiko and Akira. Their bodies had probably been swapped, and now they were having sex. The sight of them having sex seemed mysterious and precious to them.

　Despite the fact that both men are heterosexual, Norio has a fiancée, and Heihachiro has a wife and children, they cannot take their eyes off the sight of strong men's cock and asshole making a sound in front of them. Naturally, they feels the blood rushing to their erect cocks.

“Unbelievable♥♥ Akira's ass is sucking on my cock♥♥♥”

　Without regard to their gazes, 【Natsuhiko】 kept shaking his hips, leaking out a pitiful voice. His hips were gradually getting faster and stronger, which was a proof that he was reaching his climax.

“I was so excited, I cannot stop myself from cumming♥♥ I'm cumming with Natsuhiko's cock♥♥♥”

　With a beastly yell, 【Natsuhiko】 ejaculated a large amount of his cum into 【Akira】's anus. His cum shot so vigorously that even Heihachiro and Norio could hear the sound, quickly filling 【Akira】's intestines and flowing backwards, overflowing his asshole. 【Natsuhiko】 smiled in ecstasy at the volume and vigor of his cum, and gently stroked his own cum-covered cock, which he pulled out of 【Akira】's anus.

＊

　Akira Kawai is twenty-five years old. As mentioned above, he is a genius since the beginning of Eisai University. His beautiful face attracts many female fans, and he is well-known even within the university. However, he is in fact a homosexual, and is fed up with the romantic approaches he receives from those around him on a daily basis. Akira, however, has an ongoing crush on someone.

“Oh～～♥♥ Huhhh♥”

　Akira's muffled gasps echoed through the dimly lit room. Wearing women's clothing and underwear, he was still dressed as a woman, his hands and feet bound to the four corners of the bed, and his cramped asshole was being fucked by Natsuhiko.

“Nnnn, ah……♥♥”

　In addition to Akira's high-pitched, charming voice, the sound of lewd water leaking from two men's joint can also be heard. His face is contorted in anguish, but it also shows a hint of pleasure, and the sight of such a beautiful, sad, and lewd figure makes it impossible for Natsuhiko, who has a strong sexual appetite, to suppress his arousal. With a face like a beast preying on its prey, he bared his canine teeth and began to buck even harder. Natsuhiko's huge cock, which would make even a woman scream, entered Akira's body up to the base, and then was pulled out. Every time a sound was made, the fluid leaking from his asshole splashed around, moistening the sheets.

“Your asshole is the best……♥ You're sucking my cock so deliciously♥♥♥ Ah! I'm cumming♥♥ Impregnate you, Akira!! I'm going to pour my extra thick cum into your pussy!! I'm going to fill your vagina with my genes♥♥♥”

“Natsuhiko～～～♥”

　As if he was seeding Akira, a large amount of Natsuhiko's semen was spewed out and violated Akira's intestines while flowing backwards. Akira's tongue dangled from his tongue in ecstasy as he was entranced by the heat that continued to spit out from Natsuhiko's thick, pulsating cock over and over again.

“Hehehe, good job. Then I'm going to take this again today──”

　Akira's shoulders were still shaking from the excitement. Natsuhiko pulled a 10,000 yen bills out of Akira's wallet, counted the number of bills with a sniff, and patted Akira's cheek lovingly. Akira seemed to be touched by his touch and let out a sweet sigh of pleasure. Natsuhiko saw him and smiled more and more.

“I love you……, Akira♥ You are the best 【woman】. Next time we meet, please prepare more 【proof of love】 for me, my love♥”

　Throwing Akira's lightened wallet on the bed, Natsuhiko whispered to him and left the room without showing even a trace of regret. Left alone, Akira let out a sigh with a downcast face at the thought that they could not even feel the afterglow of the sexual act together.

　The year he started working as a researcher in the brain science laboratory. The moment he passed Natsuhiko in the research building, Akira's heart was captured by the sexiness of his body. It was love at first sight. He had an angular chin reminiscent of a Niou statue. His eyebrows were thick and dignified, his eyes sharp like a bird of prey. A nose with a strong sexual appetite. A muscular body covered with abundant muscles that befits such a fearless face.

　Everything about him was ideal. Akira's soul trembled with the desire to be Natsuhiko's female. As his desire to be held by Natsuhiko increased day by day, Akira finally called Natsuhiko and confessed his feelings to Natsuhiko. He, too, seemed to have feelings for Akira, and he responded to Akira's feelings.

　This was several months ago, and since then, Natsuhiko has forced Akira to wear women's clothing on many occasions, as he does today, and has violated his beautiful and supple body, even asking him for money. Akira was not angry or saddened by his selfishness, but rather pleased. Because Natsuhiko's sex was more pleasurable than anything Akira had ever experienced before. Natsuhiko treated Akira as if he were some kind of sex toy, but the pleasure his strong body gave Akira was irresistible and sweet enough that Akira didn't mind.

　But the time was approaching when those days would come to an end. Within a short period of less than a year, Akira's savings had begun to run out. He had applied for numerous patents and earned a huge income, but Natsuhiko's extravagant spending had gone far beyond that. Akira's savings were no longer worth more than a drop in the bucket. At this rate, Natsuhiko would abandon Akira.

　It was then that Akira happened to come across a thesis. It was a thesis on Heihachiro's 'Body Swap', which Natsuhiko had left in Akira's room. It was the moment when a suspicious light flashed in Akira's eyes.

＊

“How was our sex? Wasn't it erotic?”

　Akira, who had swapped bodies with Natsuhiko, removed the patches from his temple and asked in a tone that could only be that of 【Natsuhiko Hirakawa】 himself. The way he spoke and acted was so natural that Norio involuntarily gulped and spat.

“I can't believe that Natsuhiko's and Akira's bodies were really swapped…… And what's with that way of talking? It's just like Natsuhiko himself.”

“It's thanks to sex, I guess. Because I ejaculated in the body that had been swapped, our minds and bodies became fully accustomed to each other. The brain waves of the mice used in the experiment returned to their original pattern when they had sex after being switched, right? It seems that the 'mental and physical fusion caused by the strong stimulation completely swapped the two' was the correct guess. Incidentally, I used these because I thought there was a possibility that after sex, the previous memories could be erased.”

　The white patches that Akira pulled off from his temple and scrotum earlier. Taking that same patches out of 【Akira】's lab coat pocket again, he begins to apply it to Norio's and Heihachiro's bodies.

“Hey, what the hell are these?!”

“These? These are the 'Memory maintenance patch' I developed when I was 【Akira Kawai】. If you wear it, you will never forget any memory.”

“We can keep our memories on……?”

　Norio was taken aback by Akira's confident smile as he told this seemingly unbelievable story. But now that he has seen it happening right in front of his eyes, and now that they have succeeded in their out-of-this-world experiment of 'Body Swap', he feels he can believe anything now.

“Come on, then, you two can devour each other's bodies like we do, and you can swap bodies completely♥”

“We men don't have sex with each other…… We're not going to do that, right, Professor Heihachiro?! ……Heihachiro?”

　At Akira's push, Norio was almost tempted to do so for a moment. Ever since he realized that he and Heihachiro had swapped bodies, his crotch has been tingling every time he sees his former self in his vision. Somehow, however, his rational mind has managed to hold him back. Even he can hold back like this, though only barely. Akira's sweet words would not deceive Heihachiro, either. Norio had no doubt in his mind, but──.

“What……? What did you say, Norio……? Ever since I became your body, I can't control my overflowing sexual desire…… want to shove this cock up your ass and fuck you so hard……♥♥”

“No way! What are you saying, Professor?! Please come to your senses!!”

　Without hearing Norio's words, Heihachiro crawled on the ground like a caterpillar and approached him. Norio is now in the body of 【Heihachiro Okura】, who is approaching his mid-forties, when his sex drive begins to wane. On the contrary, Heihachiro has become the body of 【Norio Makita】, who is in the midst of his sexual vigor. The gap between the two was so intense that his brain was dyed pink.

　With a smile on his face at his hideousness, Akira unbuckled his hands and feet. Heihachiro instantly dives into the bulge between Norio's legs. He doesn't show any expression of disgust at the underwear that emits a strong male odor, on the contrary, he even rubs his cheeks and looks really happy.

“Ohhhh♥♥ 【My】 cock is right in front of me……♥♥”

　Unable to resist the temptation of its lewd smell, he sucked on 【Heihachiro Okura】's erect cock through Norio's underwear.

“Please stop, Heihachiro!!”

　When Norio wiggled his body while screaming in a wild voice, it seemed to touch Heihachiro's heartstrings more and more, and he shook his head back and forth violently again with an obscene expression on his face.

“Muchu♥ Reroh♥♥ Haa♥ This is 【my】 smell……, I can't get enough of the stink♥♥ Nggg.……, hmmmm♥♥”

　Norio's crotch is getting wet with Heihachiro's drool. The warm feeling through the cloth and the sticky tongue. And above all, the immoral sensation of having that Professor Heihachiro sucking his cock. Norio had managed to resist, but once his underwear was slipped down and he was directly sucking on the cock, there was no way he could resist any longer.

“Oh, gosh……♥”

　Norio was intoxicated by the sensation of receiving a blow job. Heihachiro, elated by his reaction, exposed his own raging cock. He must have already ejaculated with his underwear on. His erect cock was wet and shiny. Norio gulped at the sight.

　A cock he had seen enough of for more than twenty years to get tired of seeing it. But, from the point of view of a stranger, it was just too fascinating and stimulating. The swollen, bright red glans. A grotesquely magnificent trunk of flesh with blood vessels protruding. Once he experienced the sensation of it being placed against his asshole and pushed unceremoniously inside, Norio had no choice but to react. 【Heihachiro Okura】's cock, which he had somehow managed to restrain, suddenly stiffened and warped, and began to drip a thick, clear nectar.

　His own ecstatic expression, which he himself had never seen since he was born. The fearless face of a dreamy look on man's one is reflected in his vision. Heihachiro's sweaty skin rubs against Norio, and an obscene scent mixed with a sour-like body odor passes through his nostrils. It is the smell of the perfume his fiancé gave him for his birthday. The moment he smelled it, Norio was clearly aware that he was being raped by 【himself】.

“No, Professor! If you fuck me any more, we'll……, nmmm ……!!”

　Heihachiro slips his tongue into Norio's mouth, which he opens to reject Heihachiro, and he begins to fuck even Norio's mouth. The sensation of Heihachiro's tongue entwining with Norio's mouth and licking the underside of his gums sends a shiver down his spine. Kissing a man. It is an unknown sensation, a mixture of disgust and excitement. Norio forgot his resistance and became engrossed in the kiss Heihachiro was giving him. The kisses that devour his lips to the point where he finds it difficult to breathe imprints a pleasure in Norio's brain that is unmatched by anything he has ever experienced with women.

“Nn, fuu……♥”

　A sweet voice naturally escapes from his nose. Perhaps pleased with his reaction, Heihachiro began to play with Norio's nipples with his fingertips while deepening the kiss even more. Norio's body trembled under the skillful caress, but he intuitively understood that this was the foreplay procedure that Heihachiro and his wife always followed during sex. No, it would be more correct to say that the strong stimulation had awakened 【Heihachiro Okura】's memory. This triggered the memories of Heihachiro to flow into Norio's brain like a muddy stream. Heihachiro's wife and children, whom Norio had met only once before. He had even forgotten their names, but memories of them came back to his mind. And the half of his life spent as 【Heihachiro Okura】 runs through his mind like a flashback.

“Your memories come flooding back in my head, one after another, and it feels too good♥♥ I'm going to become you♥♥”

　Apparently, Heihachiro is also tormented by the same phenomenon, and his body twitches and convulses as he makes charming noises. Meanwhile, his hardened cock is roughly rubbing the glans against the intestinal wall, trying to stir inside Norio's body. The sensation of his asshole being forcibly pushed open. The numbing sensation of the glans gouging into the folds of his flesh, each time it penetrates to his brain. The two of them were so absorbed in the perverse pleasure that they felt as if they were losing themselves every time they were flooded with the memories of others, that they were moving their hips against each other.

“【Norio】, I can't do it anymore……. I'm cumming♥♥”

“I'm cumming too, 【Professor Heihachiro】♥♥”

　They reached their limits almost simultaneously. Heihachiro gushed cum into Norio's intestines, and Norio squirted profusely from between his legs. In this way, everything about the two of them was completely swapped.

＊＊＊

“I thank you all for being here. I can only thank you all for the joy of being able to experiment again.”

　The year after the four of them swapped bodies. The 【BODY SWAP LABORATORY】 was able to welcome five new researchers as a result of the publication of the research results. Although their physiques varied, they were all macho men, with a heroic look on their faces. In addition, all of them have a special proclivity for 【Body Swap Fetish】.

“For now, let's start with 【random】 and swap bodies, shall we?”

　Heihachiro tapped the enter key on his keyboard, and the faces of everyone in the room lost their animation. But it was for a short while. When they regained consciousness, they looked at each other and let out a hot sigh when they saw their own bodies spread out below them. Then, in a cage placed in the corner of the room, several mice began to mate.

(End)