Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/12087660.
  Rating:
      Explicit
  Archive Warning:
      Underage
  Category:
      F/M, Gen
  Fandom:
      Bishoujo_Senshi_Sailor_Moon_|_Pretty_Guardian_Sailor_Moon
  Relationship:
      Tsukino_Shino/Tsukino_Chibiusa
  Character:
      Tsukino_Chibiusa, Black_Lady_(Sailor_Moon), Tsukino_Shingo
  Additional Tags:
      Loli, First_Time, Age_Up
  Stats:
      Published: 2017-09-13 Words: 3527
****** A Show of Maturity ******
by WestOrEast
Summary
     Chibi-Usa is upset. Usagi refuses to take her seriously, and treats
     her like some kid. But she has a plan on how to show her that Chibi-
     Usa is just like an adult! And Shingo is the perfect guy to use.
     A commission for despairman.
                              A Show of Maturity
 
Chibi-Usa was upset. Stupid Usagi was getting on her nerves again. Always going
out on dates with Mamoru and kissing and not paying attention to her. Not that
she wanted stupid Usagi to fawn over her! Chibi-Usa just couldn’t see how Usagi
and Mamoru were her parents. They weren’t at all like Queen Neo-Serenity or
Prince Endymion. Well, she could kind of see how Mamoru was like her father.
But not Usagi!
 
Chibi-Usa walked down the neighborhood street, grumbling to herself. She’d show
them! She would show those two (but mainly Usagi) that she could go with them
to fancy restaurants and the beach and all those other places they went to that
Usagi stopped her from going along with.
 
Maybe, maybe if she could show that she was just as grown-up and adult as
stupid Usagi, then she could insist on coming along with them. Chibi-Usa nodded
to herself. The logic checked out. But how to show it? She didn’t have the
money to pay for meals or tickets like Mamoru, or to buy pretty clothes. What
else could she do to show she was equal to a grown-up?
 
Chibi-Usa walked along aimlessly in thought, pondering the question. Finally,
it came to her. She could show she was equal to a grown-up by looking like a
grown-up! It all made perfect sense. She’d been an adult once, and she could do
it again.
 
Chibi-Usa hadn’t had a reason to use it since Wiseman forced it through her
system. But she still remembered how to become Black Lady. It was more of a
physical transformation than a mental one, after all. Just a few seconds of
concentrating, and it would be done.
 
Chibi-Usa stepped into a quiet corner and shut her eyes. She forced her
thoughts downward, reaching for that pool of power in her breast. Tapping it,
she guided its flow through channels that hadn’t been used since her time
captured by the Black Moon Clan.
 
Chibi-Usa felt herself grow into Black Lady. When she opened her eyes, she was
several feet taller, and was barely recognizable anymore. She gave her body a
once over. Long legs, showcased by the high slit in her dress. Hair that almost
brushed the ground in two pink tails. Obvious cleavage. Pretty jewelry. Yep,
she was exactly what a sexy woman should look like.
 
Thus reassured, she set back out, looking for someone to demonstrate her
maturity with. Guy or girl, she didn’t care which. Or who, for that matter.
Just so long as she could show that she was a real adult, who should be brought
along on real adult dates. Black Lady stalked off into the night, hips swaying
as she confidently walked around in high heels.
 
Black Lady wasn’t quite an illusion, but also wasn’t quite real. She could
interact with the world just fine; pick objects up, eat, talk, all the expected
activities. But, at the same time, if she didn’t keep a large portion of her
will focused on being Black Lady, she would quickly and cleanly revert to
Chibi-Usa.
 
Black Lady paused. She was in the middle of a park, and evening was turning to
night. The sun was falling below the Tokyo skyscrapers, leaving a chill in the
air. The park was almost deserted. She could see just one figure, black in the
dying light, in the distance. Black Lady set out for it. This one would be the
one to show off with, she decided.
 
She walked towards them, making sure to put extra sway in her step. As Chibi-
Usa, high heels were a bizarre mystery, best left to others. As Black Lady, it
was like she’d been born in them. And, in a way, she had, she supposed.
 
As the two of them drew closer, Black Lady could make out more details of the
person. Presumably human, though you could never quite be sure in Tokyo. Either
a short adult, or a normal ten year old, probably male, wearing a coat… Black
Lady nodded. It looked like she had made a good choice.
 
Finally, Black Lady got close enough to see exactly who it was. She felt her
eyebrows climb up her forehead in surprise. It was Shingo. Technically her
uncle, though he’d been dead for several centuries before Chibi-Usa had been
born. Mostly she thought of him as a big brother, due to her living with him
and the rest of the Tsukino household. Actually, mostly she didn’t think of him
at all. She didn’t interact that much with the male half of the household,
mostly just with Luna, Usagi and her grandmother/ Usagi’s mom.
 
Now that she thought about it, this could work fine for Black Lady. She’d have
someone to back up her story to Usagi that they both already knew. Now she just
had to get him to fuck her. And that shouldn’t be a problem. Boys always wanted
sex, right? Minako had told Chibi-Usa that once, and as the Senshi of Love, she
should know what she was talking about.
 
Black Lady smiled at Shingo, who was watching her nervously. She couldn’t think
of why. This was how adults dressed, after all. If anything, she was a bit
conservative, with all the skin that was covered.
 
“Hello there, boy.”
 
“Hello?” Shingo’s eyes were glancing around, and he seemed to be looking for
someone. Black lady frowned. She was the only one he should be paying attention
to right now.
 
Black Lady pushed Shingo backwards. He fell onto a park bench, looking shocked.
Black Lady cruelly smiled. She’d give him something else to look shocked over
soon. She stalked forward, hands running down her dress.
 
The slit in its side went high enough that Black Lady could just pull it aside,
revealing to the world what she wore as underwear. Nothing. The same went for
her bra. Her dress provided all the support Black lady was interested in.
 
“Do you know what adults do for fun?” Black lady smirked as she twitched her
dress to one side. It was just for an instant, but enough for Shingo to get a
look at something he’d never expected to see.
 
He wasn’t properly grateful, though. Shingo’s gaze flicked back and forth,
though his gaze did keep on going back to Black Lady’s now covered legs. A look
of panic was growing on his face, though he didn’t run or cower or anything.
 
“I need an adult!”
 
Black Lady laughed. Now that was a good joke.
 
“I am an adult.”
 
Black Lady took two swift steps forward. She lowered herself down and forward,
until she was straddling Shingo. Their height difference meant that his face
was buried in her breasts. Black Lady’s dress fabric was thin enough she could
feel the heat from Shingo’s breath against her skin.
 
“I know you want this,” she whispered, caressing his face. She could feel his
desire beneath her, rubbing against her inner thighs.
 
“…Yes,” Shingo admitted, closing his eyes. He tried to bury his face in shame,
but just ended up burying it in Black Lady’s chest.
 
She laughed, and patted him on the head. Black Lady grabbed Shingo’s hands and
reached behind herself. She brought them together, making Shingo hug her.
Somehow, it felt right to be in someone else’s arms, even when she put them
there.
 
“What an adventuresome lad. Do you want to see more?”
 
Shingo muttered something that Black Lady took as a yes. Reaching up, she
fiddled with her gem-encrusted collar. Her fingers found the nearly invisible
catch, and pulled it. Black Lady’s dress split in two, falling apart before
eventually stopping, more than halfway down her torso. Her bare breasts were
rubbing in Shingo’s face.
 
Black Lady knew she had good breasts. They were high, and firm, and perky and
sensitive. She hadn’t realized how sensitive they were until she rubbed them
against Shingo’s face. She gasped, feeling her nipple drag along his cheek. She
felt herself get tingly in between her legs as she rubbed herself against
Shingo.
 
When Black Lady pulled back, her face was red in excitement and lust. Shingo’s
face was an even darker shade of red, and he had nervousness and lust written
on his face. Black Lady’s smile grew even bigger at the sight, and she humped
her hips back and forth on top of him. Shingo groaned as his cock was pressed
against.
 
“You can touch them, boy.”
 
Shingo started as the scary, hot lady on top of him spoke. He flushed, but
couldn’t bring himself to turn down her invitation. He reached up, with shaking
hands, and touched her breasts. He was a growing boy, and had the occasional
daydreams about what breasts would feel like. The reality surpassed his
fantasies.
 
Black Lady stifled a moan as her unknowing uncle touched her. Warm fingers,
even unskilled fingers, felt nice on her chest. Shingo seemed fascinated by her
nipples, and his wandering hands quickly found their way there. She had to
correct him a few times before he understood how much force and pressure he
could and couldn’t use, but soon Black Lady was enjoying herself just as much
as Shingo.
 
However, all good things had to come to an end eventually. And Black Lady was
looking for a lot more than just some breast-play. She wanted the real deal,
she wanted a hot, hard cock in between her legs. Even the thought of it sent a
thrill down her spine. Pulling away from Shingo, she raised her hips.
 
Black Lady tugged at her dress. It was easy enough to move it out of the way,
so her naked legs rubbed against Shingo’s jeans. Pushing her hips forward, she
ground against his cock, feeling it twitch. Shingo opened his mouth to gasp.
When he closed it again, it was over Black Lady’s nipple. His tongue
immediately started caressing it, stimulating that sensitive nub.
 
Black Lady gasped, then chuckled. She wondered what a Freudian psychologist
would say about a young boy unknowingly nursing at the breast of his overgrown
niece. Probably something about his mother. Black Lady dismissed the irrelevant
thought, and found that she was actually enjoying the feeling. The steady
suction, interspersed occasionally with Shingo’s tongue, felt nice. She could
feel herself growing wet as he stimulated her, his hands clutching at her
waist.
 
Black Lady did her best to push past the pleasure radiating from her chest, and
concentrated on getting to the part that would really show she was a woman. She
ran her hands across Shingo’s chest, feeling him through the thin cotton
fabric. If he wasn’t muscular, at least he wasn’t soft. But that wasn’t what
she cared about. Just touching a guy’s chest wouldn’t show that she was an
adult. She’d need his penis for that. And it seemed like he had a good one, as
Black Lady felt a length of heat pushing against her crotch.
 
It wasn’t easy, snaking her hand down in between their bodies. But Black Lady
managed it, and soon felt a large, hot rod pulsing against her hand. It was
easy enough to undo Shingo’s clothing, and pull his cock out where Black Lady
could get a good look at it. She ignored Shingo’s gasps and moans as she
touched him. He’d have a lot more to gasp about in a moment.
 
Based on her vast experience of seeing one in a medical textbook once, Black
Lady thought Shingo was pretty big. His cock was a bit taller than her hand,
and a lot warmer to the touch than she had thought it would be. Shingo reacted
in a very pleasing manner as she examined it. His head was thrown back and
Black Lady could see his hands balling into fists as she ran her hand up and
down it.
 
Black Lady raised her hips a bit, giving her room to work. She pressed Shingo’s
cock against her crotch. They both hissed at the feel of them against each
other. From this position, Black Lady could get a better feel of how big
Shingo’s cock actually was compared to her body. She thought she could take it.
It would be tight, but that was part of the appeal, wasn’t it?
 
Black Lady positioned herself over Shingo’s cock. She took a deep breath, not
noticing how Shingo licked his lips as her chest moved. She rubbed Shingo’s
cock against her lower lips. She could feel it slightly part them, and send a
shiver of sensation through her.
 
Black Lady kept on rubbing her pussy against Shingo’s cock, working up the
nerve for the plunge. As she kept on doing it, it started to feel better and
better. She looked down, and saw her arousal forming shiny streaks along the
shaft of his penis. Black Lady decided she was ready. It was time to take that
cock and prove beyond doubt she was an adult.
 
The feeling of a penis entering her for the first time was overwhelming. Black
Lady threw her head back and cried out to the heavens as she slowly sank down.
It was just too much! The feeling of her untouched walls being eased apart as
Shingo slid deeper and deeper inside her was like nothing she’d ever dreamed
of. She couldn’t, she couldn’t-
 
And just like that, Black Lady was gone. Instead of Black Lady towering over
Shingo and straddling him, now Chibi-Usa sat on his lap. There was one thing
that stayed the same, though. Shingo’s cock was still inside her. He was
inadvertently forcing apart her suddenly much smaller, much tighter walls.
 
Black Lady had thought it was all too much before. Chibi-Usa was discovering
what too much was really like. She pitched forward, falling against Shingo’s
chest. Her eyes were wide and dazed, and her mouth hanging open. Metaphors
failed her as Chibi-Usa tried to mentally come to grips with what was inside
her.
 
How the outfits of Black Lady and Chibi-Usa could change, while still keeping
Shingo’s penis intact and inside Chibi-Usa was a fascinating example of magical
garments and their application. However, neither Chibi-Usa nor Shingo knew
enough about magical theory to even begin to understand such things.
 
All Shingo knew was that the strange, sexy, scary lady taking his virginity had
suddenly disappeared. In her place, was his young cousin, impaled on top of his
dick. The pressure around him was oh so much tighter now. And yet, it was still
pleasurable. Somehow, the increased tightness meant increased pleasure, as his
cousin clamped down on him.
 
All Chibi-Usa knew was that her world had suddenly contracted to her crotch.
Shingo’s shaft had seemed large enough as Black Lady. Now that she was much
smaller, and it was inside her instead of waving about outside, it seemed like
a colossal pillar. She couldn’t gather her thoughts through the overwhelming
sensations. And what she didn’t expect was that the sensations were
pleasurable.
 
The pleasure was overwhelming, far beyond anything Chibi-Usa was able to deal
with. Her mind was filled with fireworks, obliterating any kind of higher
thought. Her fingers weakly clutched at Shingo’s shirt as she futility tried to
cope with the feelings running through her. Feeling of tightness and stretched
and hot and pleasure were all being blasted into her mind, straight from her
crotch.
 
Some instinctual part of her tried to raise her hips to get off the thing that
was filling her up, but she just didn’t have the strength to manage it. And
when she sank back down, the sensations in her redoubled. The movement of
Shingo’s cock inside her like nothing she had ever dreamed of.
 
Chibi-Usa couldn’t find the strength to pay attention to what Shingo was
saying. She vaguely registered shock and surprise, but his cock didn’t get any
softer inside her. And right now, that was what her addled mind had decided was
most important. That Shingo’s cock stayed hard and stayed inside her, providing
her with as much pleasure as it could.
 
Chibi-Usa couldn’t believe she was enjoying this. But her nipples were hard,
achingly so as they rubbed against her shirt. Something just in front of her
lower entrance was also feeling really good, sending a shock of pleasure
straight to her spine whenever it was touched. And her pussy felt good too,
even with Shingo’s cock inside it.
 
Her body and mind were slowly adjusting to the sensations. Chibi-Usa was
starting to find this ‘normal’, or at least finding a way to deal with the
pleasure. She slowly picked her head up and stared at Shingo. Her uncle stared
back down at her, in shocked arousal.
 
Chibi-Usa couldn’t remember any meaningful interactions the two of them had
had. For that matter, how did you talk to someone you were having sex with? And
she didn’t have the breath in her lungs to say anything either. All of her,
body and mind, was revolving around the sensations coming out from her crotch.
 
People kissed, didn’t they? It was hard to gather her thoughts enough, but
Chibi-Usa was pretty sure people kissed during sex. She craned her neck up, and
kissed Shingo. It was a sloppy kiss, the kiss of someone who’d never done it
before, but it was a kiss.
 
Shingo’s hands hesitantly moved down Chibi-Usa’s back. They eventually settled
on her small, flat ass. Chibi-Usa shivered at the contact, Shingo’s warm hands
seeming to cover her entire lower body. He squeezed, and Chibi-Usa gasped. It
actually felt kind of nice.
 
Then Shingo picked her up. Chibi-Usa moaned, feeling Shingo’s cock slide out of
her. And then, it slid back in as he lowered her. Her mouth opened and closed
soundlessly as she found just how good it felt to have a cock move around
inside her. Just a few repetitions of that was enough to make Chibi-Usa’s over-
stimulated body cum.
 
She shrieked, filling the night air with the sounds of her bone-deep enjoyment.
Chibi-Usa had never imagined something could feel this good or this intense.
She shook on top of Shingo as her very first orgasm washed over her, filling
her with pleasure and hollowing her out afterwards.
 
The hot, pink feelings filling her head wiped all other thought from Chibi-Usa.
She didn’t even notice that her already tight pussy was clamping down around
Shingo’s cock as she thrashed in his arms. Shingo had been feeling pretty on
edge already, from having his cousin fucking him. Her making the already tight,
wet pressure around his dick even tighter? There was only one response to that.
 
Chibi-Usa’s mind went blank as Shingo came in her. His dick seemed to swell and
he gasped, and then- Chibi-Usa couldn’t handle what was happening in her pussy.
The cum was just too much, the large, hot, thick load filling her already
stretched core beyond belief.
 
It was enough to drive her to an almost painful orgasm. Her pussy walls could
no longer clamp down around Shingo, there was too much cum in the way. Not that
it stopped her from enjoying herself. Chibi-Usa cried out as she shook in
Shingo’s lap, pressing herself against Shingo’s front. Her legs were shaking
like she’d just run three blocks, and the insides of her thighs felt sensitive
against the rough fabric of Shingo’s jeans.
 
Chibi-Usa humped her hips forward, though not even she could tell if she was
trying to get away or to get more sensation. She could feel drool running down
her chin and soaking into Shingo’s shirt as her mouth hung open. And it just
didn’t stop! Shingo pumped more and more semen into her, and it just stayed
there! Chibi-Usa wasn’t sure if she was going to burst, or blow up like a
balloon, with all the cum that was getting forced into her.
 
Shingo pulled his softening cock out of Chibi-Usa. She gasped in relief,
feeling the pressure inside her suddenly decrease. She could feel his hot cum
slowly flowing out of her tight core. She tried to lower her hand to see how it
felt, but she just didn’t have the strength. Her arms just limply dangled at
her sides as her strength flowed out of her along with Shingo’s cum.
 
Chibi-Usa didn’t think she could do anything but just sit here on Shingo’s lap.
Her breath fogged in the cool night air as she panted, feeling cum trickle out
of her. Aftershocks still ran through her body, making her quiver as pleasure
tingled inside her. She could feel Shingo quaking underneath her, too. He
seemed just as worn out as her. That was a pity. Chibi-Usa would have liked to
see what else they could do to make her feel good, without it all being quite
so overwhelming.
 
Chibi-Usa felt Shingo try and pick her up. He grunted with effort, but he
managed it. Chibi-Usa smiled to herself. He was going to take her home, and
they could both show Usagi that Chibi-Usa was just as mature as she was! And if
stupid Usagi didn’t believe her, then they’d just have to demonstrate in front
of her again. Chibi-Usa couldn’t see any flaws in the plan.
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