Reiatsu and Senjutsu

"Aizen," Tsunade began, a hint of frustration tingeing her voice. "Originally, I planned to personally oversee your initial training. Unfortunately, a sudden development at the front lines requires my immediate attention. I'll be leading a medical-nin contingent to provide support." She paused, casting a somewhat apologetic glance at Hiruko.

"This leaves your instruction in capable hands, Captain Hiruko."

"Nonsense, Tsunade-sama," Hiruko countered with a gentle smile. "We've been comrades for years. How could a simple task like this be considered a burden?" He turned towards Aizen, a flicker of something unreadable crossing his features. "Besides, guiding a talented student like yourself is an honor." Aizen, with his keen observation skills, detected a subtle shift in Hiruko's demeanor – a fleeting glimpse of an emotion that remained unreadable. 'An interesting facade,' Aizen thought, intrigued. 'He reminds me of… myself, perhaps?'

"Captain Hiruko, you're far too kind," Aizen responded, quickly adopting a deferential and slightly flustered expression. He, too, knew how to play the part. Tsunade chuckled, her straightforward nature cutting through the pleasantries. "Alright, alright. Save the formalities for later. You two will have plenty of time for that."

She sighed, a hint of weariness replacing the earlier frustration. "These endless meetings with the Konohagakure elders… always the same empty platitudes and political posturing."

"Captain Hiruko, you're dismissed for now."

"Certainly, Tsunade-sama," Hiruko replied politely, offering a faint smile that didn't quite reach his eyes. He then exited the office. Tsunade turned her attention to Aizen, a hint of amusement sparkling in her eyes. "Here you go, Aizen," she said, retrieving a green scroll from a drawer. "The Shadow Clone Jutsu you requested." This was the reward Aizen earned during his early graduation assessment."

Thank you, Sensei," Aizen responded, accepting the scroll with a respectful bow. "Honestly, can we forget with the formalities for a moment?" Tsunade chuckled. "Such rigid etiquette drives me crazy! You're young, brimming with potential. Enjoy this carefree time before adulthood sets in!"

"Respect for one's teachers is a cornerstone of any Konohagakure shinobi," Aizen countered, maintaining his serious demeanor.Internally, however, a subversive thought flickered across his mind: 'Deceiving teachers and defying tradition – standard operating procedure for a Konohagakure shinobi!' Tsunade raised her hands in mock surrender. "Alright, alright, you win, young man. Why so serious all the time? Lighten up!" Aizen's face contorted into a feigned expression of embarrassment, though he remained unfazed within. This charade was all part of the plan.

"Well," Tsunade continued, her tone turning serious, "I'll be leading a medical-nin contingent to the front lines tomorrow. However, I can spare some time this afternoon for one last lesson. Is there anything specific you'd like to learn?"

Aizen stood silently, contemplating his options...Aizen lifted his head, his gaze unwavering as he met Tsunade's. "I'd like to learn Healing Jutsu." Tsunade wasn't surprised by his request. Given Aizen's inquisitive nature, a thirst for knowledge about Healing Jutsu seemed natural. However, the complexity of the technique itself presented a challenge. Within the realm of medical ninjutsu, Healing Jutsu stood on par with Chakra Scalpel in terms of difficulty. Even among seasoned medical-nin, mastery of this technique remained uncommon. The allure of Healing Jutsu wasn't limited to its restorative properties – the ability to mend internal and external injuries with exceptional speed. It also offered the potential to disrupt an opponent's chakra flow, inducing debilitating effects, and could even be employed for remote healing within a meter's radius.

Originally conceived for emergency medical situations, Healing Jutsu's demanding chakra control requirements had rendered true masters scarce, almost a forgotten art.But more importantly, it held the potential for immense destructive power. In the hands of the rogue medic-nin Yakushi Kabuto, it had been used into a form of "combat medical ninjutsu," a far cry from its original purpose. The very nature of this technique, both intricate and potentially devastating, made it a formidable challenge to learn, akin to the legendary Madara's feats.

While Aizen's talent was undeniable, mastering Healing Jutsu in a single afternoon was highly improbable. Tsunade couldn't help but wonder – wouldn't his time be better spent tackling a less strenuous technique or resolving specific training obstacles? Despite her reservations, Tsunade didn't discourage Aizen. The entire afternoon was spent within the office, Aizen fully engrossed in learning Healing Jutsu, skipping lunch entirely.

Indeed, the technique's complexity lived up to its reputation. For all of Aizen's talent, it was only possible to achieve a foundational understanding within a few hours. Still, his progress left Tsunade genuinely impressed. "Aizen," Tsunade admitted with a hint of surprise as dusk approached, "I must confess, your aptitude for medical ninjutsu surpasses my initial expectations."

"It's all thanks to your excellent instruction, sensei," Aizen replied politely.Tsunade snorted, a wry smile playing on her lips. "Don't give me that, brat. Remember to listen next time!" After an afternoon spent with Tsunade, his carefully crafted persona seemed to be working. "You've grasped the initial stages of Healing Jutsu," Tsunade instructed, handing him another scroll. "This contains the complete technique. Further study is up to you. You can always consult Nao or Hiruko for additional guidance." Aizen offered a respectful nod.

Following his farewells to Tsunade, he hurried out of the medical department. He stopped by a random stall for a quick bite before making a beeline for his home. Once inside, Aizen secured the house and meticulously scanned his surroundings with a sensory technique. Satisfied that he was alone, he unfurled the Shadow Clone Jutsu scroll. Aizen's gaze fixated on the technique, as if it held the key to unlocking a hidden power – a way to bridge the gap between Reiatsu, the spiritual energy of the Bleach world, and the natural energy of the Naruto world.