Work Text:
The geology lab was a kingdom of order, a realm where every grain of sand had its place and every sample its meticulously labeled home. To Ruri, it was fast becoming a new home, but order was her opposite. As she hopped and skipped between machines and samples and cold linoleum floors, she frequently drew remark. How could such a small girl and her compact ass have such free run of a real academic laboratory? The truth was, Ruri liked being the center of attention.
Nagi, Ruri’s patron and the lab’s reigning deity, moved through the space with a confident grace that made Ruri’s stomach flutter. She was everything Ruri wasn’t: tall, generously curved, with strong hands that could identify a mineral by touch alone and a mind that held the deep time of the earth within it. Her focus was absolute. Ruri admired this trait, but something deep within her compelled that she shatter it.
The day’s task was monotonous but required precision: running a series of sieve analyses on sand samples from a potential new quarry site. Each bag of sand had to be carefully weighed, poured into the stack of sieves, and shaken by the mechanical shaker for exactly fifteen minutes. The resulting separated grains would then be weighed again to determine the particle size distribution. It was the foundation for a dozen more complex tests. It was also, in Ruri’s opinion, mind-numbingly boring.
Her brain began to feel a familiar, anticipatory itch. Boredom was a trigger. It whispered to her, suggesting shortcuts, little rebellions that were really just invitations for a very specific kind of attention.
“Nagi-senpai,” Ruri chirped, her voice a little too sweet. “The mechanical shaker is so loud. It gives me a headache. Can’t I just do a few of them by hand? I’ll be super careful!”
Nagi looked up from her petrographic microscope, her dark eyes softening but her expression firm. “Ruri-chan, you know the rules. The hand-shake is never consistent. The data will be compromised. The machine ensures uniformity. Use the ear protectors.”
Ruri pouted, a practiced, artful expression. “But it’s so slow.” She lingered by Nagi’s desk, tracing a finger along a beautifully formed amethyst geode. “You could help me. It would go faster.”
“I have my own work,” Nagi said gently, though a small smile played on her lips. “The data must be perfect. This isn’t a school project; the company paying for this will base million-yen decisions on our report. Now, back to work. Be a good girl.”
Be a good girl. Impossible.
“Fine,” Ruri sighed, an exaggerated sound of suffering. She returned to her station, put on the ear protectors, and started the first sample. The machine roared to life, a loud, rhythmic hum. As soon as Nagi was re-absorbed in her microscope, Ruri’s hands moved.
She didn’t weigh the next three samples. She eyeballed them, pouring what she estimated was about 100 grams into each sieve stack. She set the timer for ten minutes instead of fifteen. She even, on the last one, gave the stack a few impatient shakes with her hand before setting it on the machine, utterly defeating the purpose.
It took Nagi less than an hour to discover the sabotage. She was checking the lab notebook against the digital scales’ memory log.
“Ruri,” she said. Her voice had changed. The gentle senpai was gone, replaced by a tone of flat, disappointed authority. It made Ruri’s knees feel weak. “Come here.”
Ruri approached, covering her face with a mask of contrite innocence. “Yes, Nagi-senpai?”
Nagi pointed to the log. “The scale was tared for sample four. There is no weight recorded. Then for sample five, the weight is 103.2 grams, but you entered 100.0 exactly in the notebook. For sample six, there is no log entry at all, yet the data is written down.” She looked up, her eyes like flint. “You didn’t weigh them. And you altered the shaker timer. I heard it stop early.”
Ruri’s mask slipped. The directness of the accusation, the sheer professional disappointment in Nagi’s eyes, sent a real bolt of shame through her, quickly followed by a wave of such intense anticipation she had to clench her thighs together. “I… I thought it would be close enough,” she mumbled, looking at her loafers.
“Perhaps you did,” Nagi said, her tone downshifting. “But you should know better. Cutting corners in geology doesn’t just make the data worse, it creates more work for both you and me. You know that. This calls for a more memorable lesson.”
Ruri’s heart hammered against her ribs. The truth was, getting punished was no deterrent for her at all. Quite the opposite, in fact. Any time she was in trouble, a little tingling arose within her. With a reprimand, this tingling would spike. She’d feel it especially in her little kitty, and a little seepage would come out of it. If she was sent to her room, she’d start masturbating as soon as the door was closed, no porn needed. If she had to take her time out in public, e.g. standing in a corner, she might grin and bear it, but by the end her panties would certainly be soaked beyond salvageability. And if she was physically punished….
Needless to say, her parents had stopped trying to rein her in with negative reinforcement years ago. These feelings greeted her like an old and missed friend. She could already feel the first betraying dampness begin to bloom against her cotton panties.
“A more memorable lesson,” Nagi repeated. She stood, her tall frame imposing, and pulled the chair from her desk into the center of the room. The legs scraped against the linoleum with a final, ominous sound. She sat down.
“Come here, Ruri.”
This was it. The command sent a jolt straight to Ruri’s core. Her legs, feeling like they were made of jelly, carried her forward. She stopped just before Nagi’s knees. Her head bowed, but her eyes were wide to drink in the sight of Nagi’s strong hands resting on her thighs.
“Over my lap. Now.”
The words were a lightning strike. Ruri’s breath hitched. She moved with a slow but scrambled gait, as the experience of a hundred previous spankings entered her mind and she tried to sift through them to offend her punisher the least, and bent over Nagi’s sproingy denim-clad thighs. The light but immovable weight of Nagi’s hand settled on the small of Ruri’s back. The position was utterly vulnerable, and it presented her compact bottom as an offering.
“You compromised the integrity of our work,” Nagi stated, her voice cool and clinical, as if she were describing a flawed sample. “You lied in the log. That is not a simple mistake. It is a betrayal of trust.”
Yes, yes, it is, Ruri’s mind chanted. Punish me for it. Please.
The first spank landed. It was not a tentative warning but a firm, solid crack of palm against the skirt over her ass. A sharp, bright pain bloomed across her left cheek, and Ruri gasped from shock.
Oh, god, her hand is so strong. She hefts around that warhammer like it’s nothing with that hand. And now it’s swinging on my…
SMACK!
The second blow landed on the right cheek, making the marks on her ass perfectly symmetrical. The pain was a clean, hot sting that seeped through the fabric of her panties, branding her. With each impact, Ruri felt a corresponding throb deep in her clit. It was already beginning to swell, and ache, and need.
“The data must be perfect,” Nagi said, her voice steady, punctuated by another sharp SMACK. “There’s no place in science for making it up.”
There isn’t, I’m a liar, I’m a terrible girl, I need this, Ruri thought, biting her lip to stifle a moan. The heat in her bottom was spreading, flowing inward, coiling in her belly. She could feel her inner muscles clenching around her womb; the hollow within her ached and yearned. Her panties were undoubtedly soaked now. She just hoped Nagi wasn’t looking.
Nagi’s spanks continued without wavering, covering every inch of the back of her skirt. The pain was escalating and layering upon itself; each new smack ignited the tenderized flesh from the last.
She’s so focused. She’s not even angry, she’s just… correcting me. Like I’m a flawed specimen. And she’s going to spank the flaw right out of me.
The thought was unbearably erotic, even if Ruri knew that no spanking could ever cure her brattitude. Ruri’s hips gave a tiny, involuntary jerk which she tried to pass off as a flinch from pain. She squeezed her eyes shut, focusing on the dual sensations: the sharp, stinging fire on her ass and the deep, throbbing, wet need building between her legs. Like fuel and flame, they rose and fell together.
“You will redo every sample,” Nagi commanded, her hand falling again with a louder crack. “You will do it perfectly. Like you could have done before, but now you’ll do it with a red butt.”
The promise of having to shift on a sore bottom while working, of the lingering pain, sent a fresh gush of arousal seeping from her. She was grinding minutely against Nagi’s cushy thigh, using the pressure to stoke the fire higher. The struggle was immense. To keep her breathing hitched and pained. To suppress the moans. To not plead for more.
Nagi’s hand paused. Ruri braced. Her whole body trembled with need. Then, she felt Nagi’s fingers in the crack of her butt, searching inside for something. It wasn’t a bad feeling. Finally, she heard the rasp of her own zipper. Cool air hit her feverishly hot skin as Nagi tugged her skirt and soaked panties down to her knees.
The exposure was absolute and utterly humiliating. Her bare, brightly spanked bottom was on display, and the wet, glistening evidence of her arousal was now perilously close to Nagi’s leg.
“Let’s take this off you,” Nagi said. “Pounding fabric too much isn’t good, because the warp and the…”
SMACK!
Ruri had expected that Nagi would hold off the spanking until she was done talking. She was wrong. She didn’t understand a word Nagi said now. She was absorbing too much information through her butt now to get a thing from her ears. The feel of Nagi’s calloused hand on her soft sensitive skin. Against the tender flesh of her ass. Against the bones of her hip, it felt like. The pain was blinding. Ruri would now cry out for real.
SMACK! SMACK! SMACK! Blah, blah, blah.
As Nagi talked about her jeans or something, her strong and precise hand painted Ruri’s flesh with fire. Each blow sent shockwaves of agony through her, which her body immediately converted into waves of crippling pleasure. There was a hard, desperate pearl of arousal embedded in her clit, causing more maddening irritation with every jerk and shudder rubbing it against the twilled fabric of Nagi’s jeans. She was losing the battle. A low whimper, sounding too suspiciously of pleasure, escaped her. An embarrassed eep followed.
“No, Nîmes,” Nagi said. “There’s very little in the way of geology to do in Ypres.” The question had been rhetorical, but she normally enjoyed Ruri’s rhetorical answers. She was beginning to suspect Ruri wasn’t that interested in mountaineering clothes, and that made her more slightly more ticked off. She bucked Ruri up on her knee and spanked harder and faster now, focusing on the tender undercurve where ass met thigh.
That really got her. The combination of the searing pain, the womanhandling, and the rough friction against her clit shattered her completely. Her carefully constructed facade of remorse crumbled into dust as an orgasm ripped through her with the force of a tectonic shift.
She couldn’t stop it. A raw, guttural moan was torn from her throat as her back arched violently. Her hips bucked against Nagi’s leg; there was no more pretending. She shamelessly ground her clit on the denim as waves of intense pleasure washed over her. As the tension in her core broke, a hot rush of fluid squirted from her, soaking Nagi’s leg in a transparent, undeniable testament to her masochistic ecstasy.
She collapsed over Nagi’s lap, breathing in ragged, sobbing gasps. Her butt was glowing. Her mind was empty. Her pussy was soaked. As the aftershocks fluttered through her nonresisting nervous system and her inner muscles continued to clench around the ghost of her climax, the scent of her release mingled into the smell of the lab.
Nagi’s hand rested lightly on her lower back, bringing it to rest. Panting, Ruri came to. She waited, trembling, for the realization to dawn, for the disgust, for the end of everything.
Nagi was quiet for a long moment. Then she finally spoke. Her voice started stern, but as she talked an amused understanding dawned.
“Well,” Nagi gave Ruri’s sore and trembling bottom a single pat. “No wonder you couldn’t follow me. In the future, Ruri, if you want some discipline, you may simply ask for it. There’s no need to sabotage my work.” She helped the boneless brat to her feet and gave her ass a firm squeeze.
Ruri squeaked and expelled some more slime from her urethra. She expected some reproach on Nagi’s face, but there was none to see. With a blooming smile, she leaned into the bigger girl’s curves and gave her a hug.
Nagi smiled as well. “You really can be a good girl,” she added, patting Ruri’s head. “You just need a bit of help. You’ll like Imari. I just hope she isn’t jealous….”