Ignoring the way Tsunade has just said his name in a warning tone, Naruto goes for broke, reaching down and gathering the blonde beauty's hair up into a makeshift ponytail. Yanking her up off of the ground as the older woman lets out a distinctly undignified yelp, Naruto spins her around and bends her over her own desk, pinning her in place.
Now, Tsunade is one of the three Sanin, and the Fifth Hokage besides… she could easily have stopped him and countered him at any point, blocking his grappling attempt and preventing him from manhandling her into the position he's decided she looks best in. She didn't, because despite her minor attempt at regaining control over the situation, the fact is, Tsunade is helplessly aroused after drinking in so much of his chakra.
… No, that wasn't exactly accurate. Giving her some of his chakra as they'd kissed and swapped spit had certainly helped to exacerbate the situation, but Naruto wasn't about to forget how Tsunade had been acting BEFORE he'd even kissed her. The way she'd wrapped her tits around his thick, fat cock meat and was already going to town on his dick, even as he'd decided that he was going to have his way with her.
So then, was the last of the Senju just a hopeless slut? She hadn't acted this way when he was younger, had she? Did he just not notice? Or was there something more at work here? Maybe… Maybe Naruto should interrogate her, just a little. In the name of… showing his skills as a Seal Master, of course.
As he bends her over her desk, Naruto delivers a harsh smack to Tsunade's backside through her leggings, provoking a moan and a quivering, trembling sort of response from the lusty kunoichi. Then, while she's still recovering from that, he pulls a scroll out of his ninja pouch and unfurls it, unsealing the contents in the process.
As a sealing brush and a small jar of sealing ink poof into existence, Tsunade turns her head enough to look at them, not an impossible task when he's effectively unsealing them right next to her on her desk.
"… Naruto?"
Chuckling at her questioning tone as he uncaps the jar and picks up the brush, Naruto grabs the waistband of Tsunade's leggings with his other hand and yanks them down forcefully, getting them over her gorgeous, fat bubble butt. Clearly, these last couple of years in the Hokage's chair have allowed Tsunade to herself go, if the jiggle in her beautiful bottom is any indication…
"You wanted to see my Sealing Skills, right ma'am? Well, I figure I can show you some of the things I've come up with… first hand."
Tsunade looks back over her shoulder at him at that, and her brow furrows in consternation. She opens those pillowy lips of hers that had just been wrapped around his cock mere minutes before, but whatever she might have said is lost when Naruto, with a smirk on his own lips, slaps his cock down between her ass cheeks.
His massive erection hot dogs Tsunade's ass without pause, and the last of the Senju lets out a low, lusty moan as she trembles beneath him, shivering in delight. Really, he might not even need the seals if he decided he wanted to just interrogate her now… the mere threat of withholding the promised dicking might bring her in line.
But nah, he wants that Special Jonin promotion as well, and to get that, he needs to be recognized as a Seal Master by the Hokage herself… and would you look at that, he's got her right in front of her! Snickering at his own joke, Naruto wastes no time in bringing his brush down on one of Tsunade's bared ass cheeks, drawing the Seal with quick, easy swipes even as he slides his cock back and forth along her ass crack, causing her to moan and her backside to jiggle.
One might think that the jiggling and shaking would mess things up, but Naruto was a professional… and besides, human sealing required a bit of finesse to it, a finesse that he'd practiced and ultimately mastered over the last year, since he'd begun working on it. In the end, Tsunade was no more irritating a canvas to work on then any of the civilians that he'd tested these seals on in the first place.
As he finishes up, Naruto slaps his palm down on Tsunade's ass, applying his chakra to every last inch of the surface area of his hand as he does so. As a result, rather than smearing, the sealing ink glows as it dries and charges up at the same time, the seal itself activating a moment later. The effects are immediately obvious, even before the dust settles and Tsunade's ass stops jiggling from the spanking.
Where before, Naruto's cock hot-dogging Tsunade's backside was providing something of a distraction but not really doing much more than making her moan and mewl quietly to herself as she stood there, bent over her desk, now… now the Fifth Hokage lets out an honest squeal as his cock slides forward along her butt crack and her skin positively crackles in it's wake. She shrieks and then cums right then and there, orgasming explosively and squirting her juices all over the front of her own desk.
Smirking, Naruto gives her a bit to calm down, to recover… and then he dips his brush in the sealing ink again and moves onto the other ass cheek. As he starts to draw a second seal, opposite of the first, Tsunade's breathless voice pipes up from the front of her trembling, quivering form.
"Wha… What was that, N-Naruto?"
His smirk evolving into a grin, Naruto gives a 'helpless' shrug, as if to say, 'what can you do?'.
"Simple enough… it just allows me to amplify your sensitivity by however high I like. That was ten times your normal sensitivity, so what would normally just be arousing foreplay because as good as sex itself, and you came an instant later. I've dialed it back to twice your normal sensitivity, for the moment."
It shows, too. She's definitely quivering and trembling even harder now under him, as he continues to hot dog her ass, same as before. It makes it a little more difficult to apply the second seal, but not impossible.
"How… how high can you actually take it?"
Naruto doesn't necessarily stop what he's doing to pause and think about the question, because once you start drawing a seal, you almost never want to stop and start again, as that heightens the possibility of you fucking it up. But he also doesn't answer right away. Eventually though, he sighs.
"I don't know, truth be told. I've never taken it past fifty. Even that… well, the girl was fine, once I removed the seal. I've hypothesized that I could take it all the way up to a hundred times normal sensitivity, but not only would that likely burn out the seal, I think for the split second it worked, it would also burn out the wearer's mind. So you know… probably not a good idea to turn something made for fun bedroom play into an instant kill technique…"
There's a beat of silence, in which Naruto finishes up the second seal, and then Tsunade speaks and reminds him that she's the leader of a Hidden Ninja Village, a Hidden Ninja Village that routinely takes on assassination missions, for all that the Village Hidden in the Leaves markets itself as the 'good guys'.
"… Could be useful for our kunoichi to learn for seduction missions all the same."
Letting out a grunt, Naruto slaps another chakra infused palm across the second seal and activates it as well. Then, before Tsunade can question what THIS seal does, Naruto slides his cock back out of her ass crack, lines it up with her dripping wet twat, and thrusts forward, while at the same time ratcheting the effects of the first seal up to three times sensitivity.
Needless to say, Tsunade makes quite a perverted noise as she embarrassingly cums upon entry, her tight wet walls clenching and squeezing down around his cock quite delightfully. As he plows deep into her pussy, Naruto grabs her by both ass cheeks, not having to worry about his seals now that they're dried, and begins to grope and knead her buttocks to his heart's content, even as he leans into it, fucking her from behind with all his might.
"Ooooooh! Oh, oh, OHHHH!!! Fuck! Fuck, don't you dare stop! Oh FUCK, sex has no right feeling this good! Your cock! Your cock is so biiiiig!"
Naruto chuckles darkly at that, before slowing down just a bit.