Yo! Anyway, this'll be my very first KHR fanfiction. This awesome (and perverted) fanfiction is dedicated to my second year homeroom class but most especially to my little Yamamoto. My… parting gift. Heh.

I never give warnings but since I posted the link in our class account...well, you get the point. Not a lot of not innocent people out there.

WARNING! WARNING! WARNING! This fanfiction is purely YAOI. No girls, just boy to boy loving. /squeals

Also, I wrote it quite vividly so...prepare yourself.

On with it! Oh, and review and I will love you.

X+ Male Reproductive System for Dummies +X

Books would be the smart way. Yes, it would be better to use the smart way.

Tsunayoshi Sawada was in front of several books on the male reproductive system.

He could still remember how that librarian looked at him like he'd grown another head. What's wrong with wanting to know more about your body, hm? But the tenth Vongola boss would definitely kill himself is someone found out about this. Except maybe the person who was supposed to be helping him on his project that day.

Flashback…

"H-hibari-san, what are you doing i-in class…?" Tsuna was fidgeting with his shirt. The presence of the older man made him feel strange and weak at the same time.

Hibari looked at him with a blank expression and answered, "Isn't that what students are supposed to do in school?"

The brunette flinched at his answer and replied, "W-well, it's just that you're always…biting people to death." Was that the right thing to say, even? The cloud guardian broke out an airy laugh. "Something interesting is about to take place, you see." With that said, he took a seat behind Tsuna.

The said man shrugged what he said and sat down, just in time for the teacher to be entering their classroom.

"Good Morning class. I see that you're all present. I hope you all had a good weekend? Now, let's start this wonderful week with… a project!"

Seriously, that damn teacher must be sadistic. He's driving his students insane. And, he looks like Pedobear. It's not an understatement too.

"This week until the next, we'll be talking about the reproductive system!" Oh, insert the groaning here. "Now, now. I'd like all of you to come up with an interesting report on the gender that will be given to you and your partner." He continued talking, taking constant glances at his clipboard. "I've already assigned the grouping, suggested by an astonishing professor I met last weekend."

Oh, god. Was it…?

"Who has incredibly curly sideburns."

Reborn, you bastard.

"So! Here are the groupings…" He continued talking, and the Vongola boss couldn't order his mind to listen. It's been like this for such a long time now.

Maybe this explains why his scores range from 15 to 25.

"…Tsunayoshi Sawada." Though when he called the brunettes name, his head shot up. The teacher said, "Tsuna. You will be paired with…" He glanced at the clipboard again, "…Hibari. Yes, Hibari Kyoya."

When he heard a light chuckle behind him he thought again: Reborn, you bastard.

End of Flashback…

And so, he was there.

Tsuna held up a book entitled, "Getting to know You!" with a pubescent boy wearing a goofy grin on his face pointing at the pelvic area.

People these days. They'd do anything for publicity.

Putting down the book, the brunette decided to buy a resource material which would be more helpful. With a smirk on his face, he pays for the book and makes his way home where Hibari would most probably be waiting for him.

The Male Reproductive System for Dummies.

"Tsu-kun, you're home late!"

Tsunas mother has already finished making dinner and the table's been set with the whole family. Except, of course his father wasn't there.

Strangely, Reborn was looking intently at him. Whispering he said, "He's here." Bianchi, who heard this, decided to ignore it.

"S-sorry, mama. I'm not really hungry. I think I'll go to bed now." The Vongola boss excused himself and ran up to his room as quickly as possible.

There, on his bed was the person he already expected.

"Took you awhile, hm?" Hibari Kyoya's voice was husky, and Tsuna tried to shoo the arousal away. He placed the book on his study table before standing in front of his lover. "Sorry."

Taking a deep breath, Tsuna said, "Come on. We've gotta start on the project soon." Meanwhile, Hibari wasn't listening at all. His hands were all over the brunettes body, trying to pull off his school uniform. With those lips on the Sky guardian's neck, he couldn't utter words properly. With all the strength he could muster, Tsuna pushed Hibari away and the older man scowled. "What was that for?"

Tsuna who was now flustered, panting slightly and garnering a pretty shade of red across his face said, "I told you. Project. Come on, Kyo-chan, you shouldn't let me fail." He forged a pout and Hibari glared at him. He knew that whenever Tsuna called him that, he would end up getting what he wanted. Every damn time.

"God. Alright, alright. But I better get a prize if you get an A, alright?" he said with a smirk.

And so, Tsuna picked up the book from his table and they started reading it on the bed.

"Do you get it now?" The Cloud guardian asked, yawning a little. This was starting to bore him. All these… penises.

Beside him, Tsuna was still reading the book intently. Frustrated, Hibari began poking him on his cheek. "Oi, Tsunayoshi. Tsuna…" When the younger man finally decided to look at him, he asked, "What is it?" Sighing, Hibari answered tiredly, "Can we do something else now?"

For a moment, the brunette was quiet. At the same time, Kyoya wondered what he was thinking about. But before he decided to poke him again, Tsuna snapped back and in a split second, he was on top of Hibari.

"Hey, Kyo-chan…" Tsuna whispered against his guardian's ear. The said guardian just shuddered at the smoothness of his voice. "…you're getting bored aren't you? Well, how 'bout I show you what I learned so far?"

Without a moment to spare, the Vongola Boss' lips were already against Kyoya Hibari's, molding and pressing their bodies together. Tsuna licked his lover's lips and Hibari gave in almost too eagerly. But not really allowing himself to bottom, the Cloud guardian tried to flip their positions, only to have the brunette grab his lower regions quite abruptly. Hibari knew it was a futile effort. Tsuna broke the kiss panting. "Now…let me start educating you."

Making his way down south, Tsuna began nipping at the bare skin below Hibari's jaw. Hibari shot his head back in pleasure, feeling the painful then satisfying feel of his lover's teeth against his pale skin. "G-get…get it over with… T-tsunayoshi…" he moaned.

Fingers began fluttering everywhere as the current seme unbuttons Hibari's shirt, leaving him topless under the florescent light. As if suddenly remembering, Tsuna took something from under his pillow. The panting Hibari's face garnered a curious expression.

Tsuna took out three dying will pills.

Horrified, Hibari stared. "Y-you will not, Tsunayoshi. Don't d-" Too late. Tsuna swallowed the pills, and the Cloud guardian twitched. His ass wouldn't last long now.

Most people would think that Hibari was the 'master' of their relationship.

God, were they wrong.

Not that he was always bottom, oh no. But there were times when he couldn't catch up on the...energy that his little vixen was exerting.

Times like right now.

"Now, where were we?" Tsuna asked. His voice was now deeper, his eyes half-lidded and above all that, there was that damn forbidden flame flickering on his forehead.

Time when he looked like a fucking sex god.

"...Kyoya~" he moaned out.

Wait, scratch that. He looked like a fucking horny sex god.

Hibari was still shirtless and he looked perfectly edible at the moment.

Wanting to break the tension, Tsuna kissed Hibari abruptly and the older man snapped out of his reverie. Too much force made Hibari shut his eyes and Tsuna could feel the triumph.

Discreetly, the Vongola boss' fingers danced their way down his lover's abdomen, then to his pelvic area playing with the button holding his jeans. All the while, he didn't release his lips.

The kisses were making Hibari light headed and he couldn't help but release continuous moans. "T-tsunayoshi…"

At the sound of his name, Tsuna found the urge to rip Hibari's trousers off.

…And so he did.

So now the Cloud guardian was writhing in pleasure on bed, left with only one article of clothing to cover his lower regions, and suffering a needy frustrated feeling.

All courtesy of the sweet and adorab—er, skimpy and seductive Hyper Dying Will mode Tsuna.

"Now, where was I?" Tsuna scrunched his nose and sighed. "You have to stop interrupting me, Kyo-chan. I keep on getting distracted." With that in mind, he removed Hibari's boxers with his incisors, all the while keeping eye contact with the raven haired man. This earned a lengthy groan from Hibari, who couldn't contain his happiness.

Proof? Yeah, check south.

"Alright. So the production of the sperm cells begin in the testes." Tsuna pointed at the area, before fondling the skin, Hibari had the best view and he nodded, relaxing under the touch. "The sperm cells move to the epididymis and that's where maturation occurs." The teacher scrunched his eyebrows and leaned in Hibari's member. "I think it's somewhere…" he licked the foreskin, "…here."

"…hah…w-wait, T-tsuna…" Moaned the Cloud, beginning to move further to the bed to relax his body a little. The brunette waited patiently, watching him with mysterious eyes and a secretive gaze.

"O-okay. I'm fine…already." Hibari said when he found a good position on Tsuna's soft sheets. The other nodded, leaning over his body again and kissed his lover on the lips before trailing back down.

"So after the epididymis is the vas deferens, the…pathway," The Vongola Boss stuck his tongue out as he tried to find the right word, but what was the right word for describing the male anatomy? "…to the prostate gland."

Without warning, Tsuna inserted his long index finger inside Hibari, making the other wriggle at the sudden intrusion. "Ah..! S-shit…" the older man cussed.

Tsuna licked his lips at the delicious sound his lover was making and it only encouraged him to do more.

He leaned over once again to Hibari, whispering in his ear delightfully. "That's it, love. Go ahead and scream." And Tsuna licked his earlobe after.

The other just glared, stuttering words like, "How could I? Your mom's downstairs." But it ended up sounding like, "H-how..Ungh, I-I? M-mom…Ah!" How adorable was that?

Tsuna smiled triumphantly. "Oh, don't worry. I asked Reborn to take them somewhere in the meantime. While we're… studying." The Cloud guardian twitched at the sound of his voice, feeling frightened. But just a little bit. He couldn't really say anything at the moment. The Vongola Decimo left him in awe and he was rendered speechless.

To catch Hibari's attention once again, Tsuna wriggled his finger which was still stuck inside the guardian. The raven haired began to gasp for air, the overwhelming pleasure made him shut his eyes.

"Where is it…" the brunette began saying under his breath. The middle finger wandered inside the tight hole, looking for a bunch of nerves which—"A-AH! TSUNA..!"

"Oh, there it is~" Sang Tsuna in an invented tune. The Vongola Decimo continued pumping into that same area and watched happily as Hibari's toes curled in pleasure and his back arched at the never ending throb in his lower region.

S-shit… was the only word registering inside the Cloud guardian's head.

Oh, and So… c-close…!

But everyone knows that HDW Tsuna and his super intuition is always a step ahead everyone else. Except maybe Reborn.

And it was totally expected when the brunette harshly pulled out his finger from Hibari's hole. Well, sort of.

Kyoya Hibari's eye twitched and he slammed his head against the pillow he was supposed to be leaning on (yet forgot when Tsuna began doing his… thing) in frustration. His voice was frail and anything besides what other's thought of the Cloud guardian. Yet for Tsuna, it wasn't that… unusual anymore. "N-no…why did you…hah…w-why did you take it out..?" He complained.

Chuckling, Tsuna began lazily dragging his fingers along the raven haired man's long and slender legs. "I want you to beg, my little Kyo-chan~" He smirked against the new patch of reddish skin he bit as a mark.

Hibari heard his own jaw lock at the suggestion. It even sounded like a command. A terrible, terrible command.

You have more pride than that, Hibari.

The humming Tsuna traced the almost invisible veins in Hibari's leg, heading up to his abdomen, then back down.

Don't give in…

Almost immediately, the grazing finger was replaced with a hot and slick tongue. Teasing and kissing the skin all around.

Don't giv—aw, to hell with it.

The older man released an expression which sounded like a "Tch."

And the Tenth Generation Vongola Boss knew that his Cloud Guardian was petty in his hands.

"P-please… Tsunayoshi…" he began, almost inaudibly. Hibari shut his eyes tightly in embarrassment, sexually frustrated tears forming at the edge of its closed lids.

Tsuna pretended not to hear his voice, and leaned his ear a tad bit closer to Hibari's upper body. "Come again?" He teased in a fake innocent tone.

"Tsunayoshi…" the aloof man started again, this time a little clearer, but it didn't keep him from swallowing hard. "I-I…" and stuttering. "I need you… i-inside me. Not your fingers. Y-you…please..? It hurts, Tsuna…"

Yeah, all hell broke loose since in less than a second, Tsuna's tongue was inside Hibari's mouth, his hand stroking the raven haired man's desperate cock and his own member entering the Cloud guardian's tight entrance.

The Vongola Decimo's hands were gripping Hibari's waist tightly, using it as support so as not to hurt the older man. Kyoya's eyes shot open at the incredibly large member making its way inside him. No matter how many times they do it, it's always a bit large for the prefect. "Ngnn…s-shit…" Cursed Hibari, and Tsuna distracted him with his mouth, swiftly running his tongue over Kyoya's lips like a secret password to get to the inside cavern.

Hibari was just too happy too oblige.

Meanwhile, Tsuna's other hand attended to the Cloud guardians member threatening to burst any minute now. Stroking lewdly, Hibari gasped and wriggled at the pleasure emitting from different parts of his body. Tsuna's body tensed when he felt the member buried deep inside Hibari hit the same bundle of nerves that made the older man wild.

"Ah! T-Tsuna…more, p-please!" Screamed the man beneath the Decimo, and it only added fuel to the fire. Tsuna thrusted deep within Hibari in fast paces, moans and lustful groans leaving their lips.

When Tsunayoshi felt the walls within Hibari tighten, he lifted the prefects legs to hook them to the Sky guardian's shoulder and pumped into him roughly to catch up with his lover's euphoria.

"Oh God, oh God. T-Tsuna… Tsuna!" gasped Hibari when his release came, spurting white hot liquid across his chest and Tsuna's. After a couple more thrusts, the Vongola Decimo's legs gave in when he felt himself explode inside Kyoya, and he collapsed against Hibari's chest.

After a few minutes of deep breathing and catching of breaths, Tsuna traced Hibari's arm slowly with his finger. "The sperm cells… are released through the urethra, exiting the body and into the female reproductive system."

Hibari chuckled, wiping away the strands covering Tsuna's angelic face and the flame on his forehead diminished slowly. "You have good memory." Commented the raven haired. "Just don't forget your promise." Tsuna nodded, and before he could drift off to the invites of sleep, his lover carried him to the bathroom to clean themselves off.

That was a pretty helpful book. Thought Tsuna as he snuggled against Hibari.

"Gokudera Hayato. As usual, a hundred." Said the droning voice of their biology teacher. He handed the test paper to Gokudera, who took it without giving a damn. "Tch. Who the hell would fail the stupid reproductive system test?" He scoffed.

The whole class except for him, Yamamoto and Kyoko pointed at Tsuna.

"W-what?" The dumb brunet asked, looking more lost than usual.

The teacher waved the fingers out of the way as he approached the Decimo's table. "Tsunayoshi Sawada. 95. Not bad, Sawada. Any secrets? Cheating perhaps?" Teased their teacher.

Tsuna defended himself by saying, "I didn't cheat!" And he heard Yamamoto's light laughter. "Wow, Tsuna! Awesome!"

Kyoka-chan too. "Tsuna-kun, good job!"

But of course, there was Gokudera. "JUDAIME! THIS IS GREAT! WE SHOULD CELEBRATE! I'M CALLING REBORN AND FUUTA… OF COURSE MY SISTER WOULDN'T BE INVITED…" and he's back in his own world.

Tsuna scratched the back of his head laughing.

Don't forget your promise.

This memory made Tsuna smirk under his bangs. Worry not, Kyo-chan. I won't.

Meanwhile, the prefect was secretly watching his lover through the window and leaned against the tree branch.

"Hm, now to get my handcuffs ready." He said to himself, jumping off the tree.