Naruto- Secret Sage

Draw blood

I saw my sensei's look and scoffed "Don't make that face at me. Is it any surprise that I would try to categorize and add logic to even something like romance given how well you know me? As I said earlier I believe we were too young to think about such things and thus hadn't had any such feelings towards Karin unlike her towards me. That may change now that I am aware of it but you can't expect me to suddenly fall head over heels for her." I said and she thought about it for a moment before sighing and nodding in agreement.

Nothing I had said was wrong given the circumstances and sad as that may seem assuming that me knowing how Karin felt would automatically make me reciprocate those feelings was flat out foolish. Karin was a good choice of partners for me to begin with since we got along quite well after living together for so long so while learning she held feeling for me came as a surprise I wasn't against the idea of pairing up with her. Honestly it wouldn't really change much as far as I saw it beyond taking us both off the market.-

"So are you going to start dating now?" my sensei asked curiously.

"Up to Karin. I'm not the one pursuing her after all but rather it's her that pursues me so naturally she will need to put in the work if she wants to get me." I said honestly.

"I almost pity the girl given your high standards in every other regard." she said with amused look.

"Enough about that though, I need to understand fully what the snake that bit me has done to me before I seek it out to cut off it's head." I said seriously and she nodded.

"I've tried to take blood samples after this transformation finished but well I failed. Your body is too tough to pierce through with any needle now, not even the chakra metal ones he used to cause this. I thought of using chakra but not even my chakra scalpel could leave more than a white mark on your skin." She said with a helpless look.

"Hmm, give me a moment." I said and created a claw of chakra on my pointer finger that I then pressed against my wrist hard.

"SKKKKRRRRREEEE!"

The sound of metal grinding against metal sounded out as my claw slid across my skin but failed to penetrate at all.

"Fine then, the hard way it is then." I muttered and reabsorbed the chakra claw before projecting chakra out of my finger again that swirled before forming a small bead sized lightning [rasengan] that I sent straight at my wrist. 

Sparks flew as the miniaturized jutsu drilled against my skin and I finally felt some pain as it started to dig ever so slowly through my skin to hit a vein at which point I hurriedly tilted my wrist sending the small jutsu harmlessly through the floor as it was deflected.-

"What was that jutsu?" my sensei asked curiously while not wasting any time collecting my blood in a vial as I forcefully fought against my own bodies healing factor to keep the wound open.

"Lightning nature [rasengan], I miniaturized it but the principles behind it still work. It could be considered an S rank jutsu specialized in piercing through tough materials. I hadn't expected it to struggle so much against my skin, fascinating is it not?" I explained genuinely amazed by the sheer defensive quality my flesh had now.

"Are you insane!? You used an S rank jutsu of all things just to collect blood!?" she exclaimed in horror.

"Not at all, even before that snake bit me I could resist most jutsu at B rank and judging by your explanation I assumed I had skipped A rank jutsu in terms of resistance and thus only an S rank jutsu or attack might work. I assure you I chose my placement for the jutsu in a location that wouldn't cause much damage even if it went fully through my arm. Between the tendons and bones at an angle for minor injury in the worse case scenario." I said calmly.

"You do understand how insane that sounds right?" she asked and I shrugged.

"It was the best option I could think of. Though now that you mention it I will need to figure out an easier way to draw blood or the summoning jutsu will become unusable for me." I said with a frown.

"I give up trying to understand how that brain of yours works. I'll get this to the lab to see what I can figure out. In the meanwhile I expect you to take it easy for the foreseeable future and I mean it Kenzo. No training at all AM. I. CLEAR?" she asked with a firm look as she emphasized those last few words.

I reluctantly agreed since while I honestly felt better than ever there was no telling what would happen if I tried to really push things. I had just gone through a fundamental transformation after all and such things were never simple matters. It wasn't exactly the same thing but it was sort of how an Uchiha was affected by their eyes the further along they develop.-

It was sort of an open secret but the sharingan caused the wielder to become colder and more emotionally unstable the further their eyes developed. This was theorized to be because their eyes made it impossible to forget things they saw including traumatic stuff. The phrase "all wounds heal with time" doesn't apply to them as a result meaning they felt that same emotion every time they recalled any incident as if they were still experiencing that incident. It only got so much worse the more drastic the transformation of their eyes as each further stage of development required a stronger emotional trigger than the last.-

My own transformation probably didn't have such a nasty side to it but I REALLY wasn't willing to test that Idea without some evidence to back it up first. I was a little peeved that I couldn't work on my chakra armor too since I felt as if my chakra was smoother and more obedient. Just the ease by which I was able to summon that claw and lightning [rasengan] earlier was proof enough for me to make that assumption as neither of those were simple techniques.