I realized, I haven't uploaded this thing on ... The world Needs more KakuTsu, they are so hot and cute together, anyway, Enjoy. (Rated T for sexual themes)

"kuzu…" Tsunade whimpered for the umpteenth time.
Kakuzu reluctantly blinked his eyes open again. "what?" he asked slightly dazed.
"You were falling asleep again…" she smiled teasingly.
"mmm…. Really now?" he sleepily remarked.
Tsunade giggled. She loved to keep him awake while she was still basking in the afterglow. She found it quite adorable that he that he could barely keep his eyes open afterwards. Then again, Kakuzu was the type of man who likes to cum at least twice during sex.
Kakuzu smirked a little as she laughed.
"Don't act like your not tired neither…"
Tsunade smiled and buried her face onto his chest.
"I am. But not as much as you. You always fall asleep more quickly then I do."
Kakuzu blinked his heavy eyelids, and they were starting to close.
Tsunade took notice he was falling asleep again, and then she started lightly tugging at his stitches on his chest muscles.
Kakuzu gave a little jolt. "A-ahh…." He moaned a little.
He stared at her. She grinned teasingly at him.
Kakuzu sighed. Sometimes, he hated being in love with the best medic nin in the land of fire. She knew exactly how sensitive his stitching was, and where exactly where to pull the threads to make him squeal in pleasure. Kakuzu hated making those noises. It made him feel like a wus. Tsunade however, found them quite adorable and slightly arousing.
Kakuzu's eyes narrowed at her.
Tsunade smiled, and slowly traced along the line of stitches on his pectoral muscle. That granted a small shudder and moan from Kakuzu.
Tsunade stopped and rested her hand there.
"you know…" Tsunade said rubbing his muscular chest, avoiding his stitching.
"mm?" Kakuzu asked, still rather tired.
"I think your age is catching up to you.." she said teasingly.
"What do you mean?" he asked.
"I always used to fall asleep before you, and lately, you've been the one who's been falling asleep on me."
Kakuzu blinked tiredly. Trying to swallow that statement.
Tsunade giggled. "You're old." She remarked.
Kakuzu grinned playfully. "Takes one to know one, granny."
Tsunade glared at him. Kakuzu laughed tiredly. Sure, she could call him old, but he couldn't call her old. Kakuzu didn't get the logic in that neither. It was just the way on how woman operated. Kakuzu blinked his heavy eyelids again and yawned. He closed his eyes.
"Kuzu…"
Kakuzu didn't open his eyes. He only responded with a: "mm-umm…"
Tsunade ran her fingers inside one of his stitches.
"Ughm…." Kakuzu moaned and he then again opened his eyes to look at her. Her face looked concerned.
"I think you really are getting up in the years. Honestly."
Kakuzu blinked. Then he stared at the beauty before him. He remembered the first time he'd seen her use the chakra stored behind her forehead, and the aftermath of it. How old and fragile she appears without her medical jutsu. He knew that's what she really looked like. It didn't bother him. But it worried him. He knew that they both couldn't stay together forever. She searched for eternal beauty. Not eternal life. He knew one of these days, she would die while he lived with his five beating hearts.
"You are too a little bit." He finally remarked.
"I know. But I'm not as old as you remember."
Kakuzu stroked his hand gently through her hair.
"But you age quicker then me.." he remarked concerned.
Tsunade looked up at him.
"but you often suffer from blood clots, heart failure, cardiac arrest, as a matter of many other problems…"
Kakuzu sighed. Why did she have to state the obvious to him like she was his doctor? He pulled her in close against his naked stitched chest and she blushed. She listened to the rhythmic heartbeats that went throughout his body.
"I doubt you'll have to worry about me leaving you. You know I have five hearts, Tsu… you can't get rid of me that easily. I'm more worried about you. Your jutsu makes you look young, doesn't mean you can live for as long as I have."
Tsunade stared at him. "So your saying out of the two of us, I'll die first?" she asked.
"It's more likely then me dying first."
"your older then me."
"Doesn't mean I'm not fragile like you."
Tsunade stared at her man. Kakuzu always stated what he thought was a fact. He never tried to sugar-coat the situation. Tsunade kind of liked that. He was bluntly honest. And with Tsunade, that earned his share of being punched through walls, but he always hardened his skin before she does so. So it never really hurts him that much. Tsunade still found it curious how he can keep loving her after she hits him from her violent outbursts so many times. But as far as she can figure, it's probably because she can put up with his violent outbursts too. Once in awhile, Kakuzu might get angry and try to kill the closest living thing in relation to where he was. Sometimes that would be Tsunade. Every time he tried to strangle her, Tsunade would block his hand and grab it and flip him so hard it would cause a dent in the floor. That would always calm him down and bring him back to his senses.
Tsunade looked up at Kakuzu, who had fallen asleep again.
Tsunade traced the stitches on his cheek and tugged on them so they got a little loose.
"O-Oh! GOD woman!" He remarked.
Tsunade giggled.
Kakuzu was beginning to get annoyed. "What? If you want another round can you wait a couple hours?"
Tsunade blushed slightly. "No, not that… I just thought of something…"
"Hm?" Kakuzu asked sleepily.
"Want to make a bet?"
Kakuzu gave a small smile. He had always loved money. And the fact that Tsunade loves money too only made her more attractive to him. He never understood her obsession with gambling though. If she always looses but he loved making bets with her. At first he just did it to humor her, and her obsession for gambling. But later, he became rather to enjoy gambling with her because he could take comfort in the security that he won't loose any money if his opponent is the 'legendary sucker'. Tsunade always gambled with him because partly because of her obsession and she knew Kakuzu can't say no to her when she asks. Kakuzu always accepted, because he knew he could never loose. They also made playful bets on everything with eachother… What food they will eat, where they should go, who's the strongest and even sometimes…. relating to the bedroom. Kakuzu liked these pointless bets. They were rather fun, even though he hated to admit. Even if sometimes if no money was involved in most of the more pointless ones, Kakuzu didn't mind accepting a kiss as a payment.
"What's the wager?" he asked liked a true gentleman.
"Who can stay awake the longest."
Kakuzu blinked. "Hey! Tsu-Tsunade, that's not fair… I'm exhausted…."
Tsunade smiled. "I know. Gives you a better reason for you to stay up."
Kakuzu smiled slightly as he stared at her with his tired eyes. "I guess I'm not going to get any sleep tonight, huh?"
Tsunade smiled, and nuzzled her head on his chest. "Nope!" she responded cheekily.
Kakuzu sighed and wrapped his arm around her, rubbing her back slightly.
"Well… I guess that's two of us…" he said tiredly.
Tsunade giggled as Kakuzu struggled to keep his eyes open.
"The stakes?" he asked.
"Whoever falls asleep first proves that they are the oldest, therefore, the one to die first."
Kakuzu blinked. "Woah. Some high stakes there…"
Tsunade grinned. "All or nothing, babe. You in or out?"
Kakuzu smiled. He loved it when she related gambling to her life. It made everything seem a whole lot easier when the world is put into terms of money.
"I've never lost to you before, and I'm not going to start tonight. I can go for weeks without sleep, Tsunade. Just you wait…"
Tsunade smirked. "Oh I will, you sleepyhead." She teased.
Kakuzu yawned. "I love you Tsunade-chan." He kissed her forehead.
Tsunade snuggled against him, feeling rather tired herself. "Me too, Kakuzu."

After fifteen minutes, they fell asleep together.