Okay, just a bit of constructive criticism...well, my opinions, but still hopefully constructive.
First, unless you've upped the ages, Naruto having a ten inch penis is really pushing the suspension of belief for even fanfiction.
Second, personally, I don't think that was a blowjob. While it may have started that way, it certainly didn't end that way. To me, Tsunami sucking his cock denotes the woman being in complete control of the movements. Now, this is just my personal stance, but once the guy starts thrusting into the girl's mouth, it ceases to be a blowjob, and becomes face/mouth/throat fucking. What Naruto was doing to Tsunade was not a blowjob, but throat fucking and gagging.
The lines about her used pussy being stretched out, and ruining her pussy for another man took away from the scene a bit. It made it feel less like a erotic scene, and more like a cheep eromanga.
Okay, now to the other stuff.
I noticed that one of the requirements for the Rinnegan perk is gained upon him having sex with an Uzumaki. Does that mean Naruto might gain that part after having sex with Karin who we've learned is an Uzumaki? Or what about Tsunade, who we now know was the granddaughter of one born to the clan, and as far as we know, possibly the daughter of one as well based on a similar situation to Mito and Shodai. If so, then it's possible for Naruto to gain the Rinnegan before the Chuunin Exams end, which would certainly be interesting. His chakra is already at 40, Karin or Tsunade could be his Uzumaki sex, unless you're deviating from canon greatly, then Kiba or Neji would be his bloodline defeat, so all that he'd need to do is ask about Nagato. Also, this is just me, but given how powerful the bloodline is, it seems that defeating two bloodline wielders should be a requirement, with Haku's Hyouton being the first.