Sakura brought Lee to a secluded laboratory she arranged in the village to practice her Medical Ninjutsu. When Lee looked around, he saw many herbs and medicines and felt a sense of wonder.
What was this place? Why did she bring him here?
"Lay your back straight on that." She pointed at a surgical table, causing him to shiver in fright.
"You aren't doing anything illegal, right?" Even Lee knew Medical Ninjutsu wasn't something you can mess around with. One wrong move and any patient could end up needing an amputation.
"You're too worried over nothing. I have a Great Teacher who is certified as a Medical Ninja. She said that i was responsible enough to use Medical Ninjutsu on others." She lied without thinking.
"Okay..." Lee accepted her explanation despite it being a little hard to believe. He had full faith in her!
He got onto the surgical table with hesitation and turned to look at Sakura, not knowing her intentions. The fact that she mentioned that he needed a 'Medical Ninja' to learn this secret technique she was going to teach him amazed him.
What kind of Taijutsu needed a Medical Ninja?
"First, I'll need to inspect your health. Can you take off those bandages on your arm?" Even though looking was enough to glean some details for a Medical Goddess like her, being able to properly scan his body would allow her to see them clearer.
Lee hesitated a little before doing as instructed. A white bandage slowly unwrapped off his arm as he made up his mind. When she saw the redness of his skin, she couldn't help but gasp a little.
How was he walking around so happy-go-lucky with arms like this? Didn't he have a sense of pain?
"Take off your shoes and show me your ankles." A heaviness appeared in her voice as she spoke to him. Lee was shocked by her tone and felt like a kid who did something wrong as he did as she asked.
He sat up and took off his shoes.
"The weights on your legs as well."
"But-"
"Just do as I said." There was a no-nonsense aura around her as she got him to pull up the bottom of his pants. Compared to his arms, they were practically mutilated to the point it was discernible.
She understood Gai-sensei's reasoning behind training him like this. Although he was hurt, Lee was probably periodically getting healed in order to strengthen his physique. This was the 'Strong Fist'.
Unlike other kinds of Taijutsu, the Strong Fist Gai-sensei taught was the kind of technique that would imbue chakra into the body the more they went through this kind of training. It was a method of slowly tempering the body with Chakra over time.
Although Lee couldn't use Ninjutsu, he still had Chakra Pathways, that's why this Taijutsu could still be trained by him. The only reason he became such a monstrous Taijutsu User in the future who could pull off superhuman feats was because of this. Rather than relying on Body Flicker or Power Fist like her, he was focusing purely on his body.
"You know... Overtraining is a thing that exists. Are you trying to die?" She put her hand on his arm.
A green light arose as she tried to heal him, but as she expected, it was harder to do than normal thanks to how she was trying to make sure his training didn't go to waste. If she healed him too fast, then the training he did would be useless.
There was a reason Gai-sensei didn't try taking shortcuts while training. As a weapon can only be forged by diligent tempering, trying to learn the Eight Gates without diligence would end up making Lee's body explode rather than turn empowered.
"This is nothing to me. After all, I am stronger than anyone!" He put a thumbs up to her in response.
Even though it was painful, he was well-aware of the condition of his body. He wasn't overtraining at all! In fact, he had enough strength right now to do a hundred more push-ups. He won't wimp out!
"...Forget it. Let me treat your internal injuries. I also want you to visit me whenever you feel like you're ill. Relax a little more..." She spoke worriedly as she didn't like how stubborn he was being.
Did he really have to break his spine before he could learn to tone it down a little?
"Thank you, but really: I'm fine!" He smiled without showing a hint of reluctance to his training regime.
"Don't you have other options?"
"Huh? Err, what...?"
"Can't you train your dream to something more easier?" She knew it was overstepping her bounds to ask him this. After all, she had already seen the lengths he would take in the future for his dreams.
"...I don't want to."
"Why not?"
"I'll feel like I lost." He shook his head stubbornlyS
As an adult on the inside, she couldn't help but find this very childish. But this reason suited him well...
"So you don't like losing..."
"Of course, my-"
"Does that mean it's fine to mutilate yourself?" Her tone was as usual as she spoke these words.
"...I'm not." For some odd reason, he couldn't bring himself to look at her eyes as of this moment.
The look in her eyes was scarier than her angry face. No, there was a lot of complexity within them.
Sakura admitted that Lee's presence was really helpful in the Fifth Great Ninja War when he finally became a powerhouse of the Hidden Leaf, but that didn't mean she liked seeing him like this.
Perhaps you could say this was the first time she got a good look at him, past that comical exterior.
"Lee."
"Yeah?"
"Promise me you won't overtrain your body again."
"..." He found it hard to give his word. The kind of training the Strong Fist required was immense.
Sakura respected his choice. So she changed it:
"If not, visit me more often."
"Of course! Anything for my destined future sweetheart!" Sakura dodged the kiss he blew.
This dork was getting too full of himself... He didn't even know how to follow the doctor's orders... How infuriating! As she was thinking of a way get him to take care of himself more, someone knocked.
She didn't even need to look to know who it is:
"Come in!" She said loudly towards the door before a 'girlish guy' came walking in with a frown.
"Is that your friend?" Lee looked at her in surprise.
"I am a guy." Even though Lee didn't ask, these words that came out of Haku's mouth made his eyes turn as round as saucers. The femininity of this guy made him initially think he was a girl...!
"Erm, hehe. Of course I knew that." Lee spoke while embarrassedly looking away from him.
"So... Sakura, is this a friend of yours?"
"I'm trying to teach him a secret technique."
"Can I help out?"
"Sure. Do you know anatomy?"
"Merely for combat purposes. I'm no Medical Expert like you are." Haku shook his head.
Lee was wide-eyed at how friendly this person was towards Sakura and vice-versa. Not out of jealousy but because he was sure he hadn't seen this person before, but Sakura kept the topic moving:
"Lee, I need you to close your eyes and focus your attention towards your heart. All you need to do is hold on and control the flow of your Chakra." Like a well-needed surgical assistant that came at a good time, Haku took out some needles in response.
As Lee didn't have the time to think too deeply, he did as Sakura instructed. Only when he did so did she proceed to try out the optimised version of the Reverse Eight Gate Opening Method on him.
Similarly to her Destructive Rebirth, there were less stages within this technique as Inner Gates were paired when opening. As she was certain Lee could handle the first level of this technique, she started to use it on him rather than teaching him the technique. This wasn't because she was stingy but because there was no 'normal' way to use it.
Gai-sensei was still at the development stage after creating this technique and there were still some imperfections even after creating it. The first being that you needed to 'survive the eighth gate' in order to gain insights to achieving the first level.
As even she wouldn't be able to save Lee should he idiotically try opening it, she acted as the external help that could get him to that stage. The only reason the Reverse Eight Gate Opening Method couldn't be taught to Lee was due to her hesitations in allowing him to figure it out after learning the specifics of the technique.
When she looked at her memory, the Lee of this time of his life would definitely do something stupid if she taught him another self-mutilating technique of this nature. She'd rather he progress safely.
"Lee, listen to me carefully now. Do NOT move no matter how itchy your body becomes, alright?"
"Easy." He was ready for the 'procedure'. He didn't know what she was doing but trusted her ability.
Sakura took some of the specialised needles brought to her by Haku (who acted accordingly when to support when he sensed the intentions she had), and placed them on him carefully.
The first two Inner Gates she was opening was the Gate of Death that released his body's full potential and the Gate of Wonder. That's why the first thing she did after putting needles on him was press the Inner Gate near his heart with her thumb to open it.
If he had opened the seven Inner Gates before opening it, the affects of it would heart up his body to the point of incinerating it from within, but opening it right now only increased the blood circulation around his body to an unnatural level.
His body heated up as a result, and she knew he wouldn't be able to handle it if continued like this.
That's why she moved onto opening the Gate of Wonder, an Inner Gate that reduced the 'shock' a previous Gate had on his body. This was the first phase to reach the first level of Reverse Opening.
The intention of opening these two Inner Gates together was to create a foundation for the second level. Normally, the Gate of Death would release his maximum potential until he 'burnt out', but by using her own Bloodline Seals, she negated this slowly.
Haku provides ice to cool Lee down and even fed him the 'Hydration Pills' on the shelf after seeing how his body was secreting a large amount of sweat to offset the heat that was building up.
Lee senses that itchy sensation all over his body yet still endured duality of hotness and coldness.
"Calm down your heartbeat." She instructed, that translated into his head as 'control your breath'.
As a Taijutsu Specialist, to 'adjust breathing' for the sake of regulating his condition was a must.
His mental limiters kicked in as he unconsciously brought his condition to its most optimum state from that moment on. There was no need for Sakura to help him anymore as he calmed down.
When he opened his eyes, he looked at himself in confusion after feeling two of his Inner Gates were still open. Normally, having them open would injure him and put a strain on his physique, but as of this moment, his Inner Gates were tranquil like a lake.
"Never open any more Gates on your own. If you want to do that, first master the first level of the technique I imparted." Sakura wiped the cold sweat from her forehead as everything went as expected.
"...How do I do that?"
"You'll know you've mastered this level once your able punch a hole through iron. Now you can train to your heart's content." She then went on to elaborating about the key features of this.
The first level of Reverse Opening was created in order to master the full extent of the Strong Fist. It allowed the user to unconsciously strengthen their body and unravel their potential much easier.
Since Lee had always been talented in the Strong Fist, she knew this would help him immensely.
"Now I have a favour to ask." After doing as she promised, she then asked something of him.
After hearing her request, he agreed with a smile.
"I can do that, no problem!"