Hikaru sighed deeply. "Shouldn't this be, like, impossible?"
"I dunno... That programme did say no twins were truly identical."
"I don't buy it! We've been looking for hours and haven't found a single difference yet! I'm never watching Discovery again!"
"And miss MythBusters?"
"...Okay, maybe not."
"Come on, we haven't even checked every part of our bodies yet."
"What's next?"
"Let's see..." Kaoru picked up a crude drawing of a human body. "We just did our bellies, so that can be crossed out." Hikaru gave a red marker to his twin, who then drew a large cross on the stomach of the drawing. "That leaves us with, you know... those places."
"Those places?"
"Yeah, our private parts."
"Oh~ our 'naughty' places, my dearest brother?"

"It would seem so, sweet brother of mine~ "
"I may not be able to contain myself, you know~ "
"Like you ever can~ "
The twins burst out laughing over their own over-the-top performance. Despite the fact that they had been playing the brotherly love game ever since they entered the Host Club, they hadn't actually done a lot of actual incest together. The most they did was jerk each other off sometimes. They hadn't even truly kissed.

"Let's get naked then," Hikaru said, before sliding off their bed and taking off his boxers. Kaoru nodded and quickly took of his boxers as well. they sat down next to each other on the bed and carefully started to examine each other's privates.
"I think you have a mole here... Oh wait, it was just a bit of shadow."
"You seem to have more hair"
"That's just because you shaved it off as a joke last week, remember?"
"Oh yeah... That was a good one."
"I totally didn't fall for it!"
"Yes you did! you almost cried!"
"Nuhuh!"
"Uhuh!"
"Nuhuh!"
"Okay, okay, you didn't not fall for it."
"See! Hey, wait... Did you just...? Nah, I won!"
"Of course you did Hikaru, of course you did."

Naturally, it hadn't taken the boys long to get fully hard. By the time they finished their comparison, they were both as horny as only fifteen-year-old boys can be. Their probing touches slowly turned into gentle caresses, that in turn became determined strokes.

"Kaoru?"

"Yeah Hikaru?"

"Wanna jerk off?"

"Do you really need to ask?"

Hikaru grinned and they both started masturbating the other in earnest. It wasn't long before they were panting softly and thrusting into each other's hands. Suddenly, Hikaru stopped.

"Hikaru? What's wrong?"

"Kaoru, could we..."

"Are you sure?"

"Would I ask if I wasn't?"

"True that..."

"Don't you want to?"

"What do you think?"

"So what first?"

"I think..."

Kaoru bend over and gave the tip of Hikaru's dick a small kiss. Hikaru gasped, but quickly returned the favour. They repositioned themselves, so that they were lying next to each other, in the sixty-nine position. Although they started out hesitantly, they were quickly licking and sucking with a vengeance, fully enjoying the tastes and feelings that were so unknown and yet so familiar. Their hands weren't keeping still, either, exploring and massaging every piece of skin they could reach.

Before long, the boys started thrusting their hips involuntarily, signalling their oncoming orgasms. Unafraid and excited of what lay ahead, both threw themselves on their task with complete abandon. At the exact same moment, both moaned around the other's dick and climaxed heavily in the other's mouth. They lay motionless for a moment, savouring their own orgasm and the taste of each other's cum. Then they sat up and embraces in a passionate kiss, the first of what they knew would be many, many more.

After what seemed like an eternity, they fell down on the bed, Hikaru resting his head on Kaoru's chest.

"I can feel your heartbeat, Kaoru. It's really fast!"

"Really? Cool."

"Yeah, it's right here." Hikaru poked the right side of Kaoru's chest, before giving it a quick kiss.

"Hikaru... The heart is on the left side..."

"No it's not!"

"Yes it is."

"Not with you!"

Kaoru felt his chest and noticed his heart beat distinctly harder on the right side. He quickly felt his brother's chest too, noticing his heart was clearly on the left side.

"You... You're right..."

"Told ya!"

"Don't you see what this means Hikaru?"

"Eh? What do you... Oh! We finally found a difference!"

"Yeah! Our hearts are mirrored!"

"Awesome! We're mirror images!"

"This is so cool!"

They cuddled up together, content with their new discovery. As they lay side by side, their hearts were side by side as well, beating in perfect unison.

"I love you Kaoru."

"I love you too Hikaru."

"You know we belong together now. Our hearts are proof."

"I wouldn't want it any other way~ "

"Me neither~ "