The Fifth Hokage, Tsunade, regarded Sasuke with a discerning gaze, her emerald eyes sharp and knowing. "As I mentioned previously, Uchiha," she began, her voice carrying a note of authority tempered by a hint of the counsel she intended to impart, "while I myself have not mastered the art of Senjutsu, my most trusted summon, Katsuyu, possesses a deep understanding of its principles and application. She is the one who can guide you on this path."
Shizune, ever vigilant and concerned for the well-being of those under Tsunade's charge, stepped forward slightly, her brow furrowed with apprehension. "Hokage-sama," she interjected, her tone respectful but laced with caution, "is it truly wise to permit Sasuke-kun to undertake Senjutsu training? The risks, as we know, are considerable. Should the balance be disrupted, the consequences of petrification are… severe."
Tsunade's gaze softened momentarily as she addressed her loyal assistant. "Shizune," she replied, her voice firm yet reassuring, "Katsuyu possesses an innate sensitivity to natural energy and a wealth of experience. She will be able to monitor Sasuke's progress and intervene should he falter dangerously. Furthermore," she continued, turning her attention back to the young Chunin, a flicker of something akin to anticipation in her eyes, "I have observed Sasuke's chakra control and his inherent connection to his own inner energy. He surprisingly possesses a significant aptitude for Senjutsu, a potential that should not be ignored."
With a decisive gesture, Tsunade reached for a meticulously rolled scroll resting on her desk. Unfurling it with practiced ease, she pointed to a blank space near the bottom. "This is the summoning contract for Katsuyu. By inscribing your name here in your own blood, you will become one of her summoners, allowing you to invoke her presence. Subsequently, she can utilize the Reverse Summoning Technique to transport you to Shikkotsu Forest, her domain, where your training will commence."
Sasuke, who had been listening intently to the exchange, offered a respectful nod. He stepped forward, drawing a kunai from his pouch. As he prepared to make the necessary incision on his thumb, a sudden thought arrested his movement. His brow furrowed slightly, and he paused, the tip of the kunai hovering just above his skin.
"Hokage-sama," he began, his tone thoughtful, "if I may pose a question. It has come to my understanding that the summoning contracts for the toads of Jiraiya-sama and the snakes of Orochimaru operate under a principle of a singular summoner per generation. If this holds true for Katsuyu as well… and furthermore," he continued, his gaze meeting Tsunade's directly, a hint of intellectual curiosity in his dark eyes, "is there not also a prerequisite, in some cases, of possessing your… Byakugo Seal to effectively summon her?"
Tsunade regarded him with a newfound curiosity, her head tilting slightly. "Indeed," she mused, her voice laced with intrigue. "How did you come by this knowledge, brat?" Before Sasuke could formulate a response, she waved a dismissive hand. "No matter for now. As it happens, while Mount Myoboku and Ryuchi Cave do adhere to such generational restrictions, the inhabitants of Shikkotsu Forest do not follow the exact same conventions. Katsuyu has, on occasion, acknowledged multiple summoners across different eras."
She continued, her tone reassuring, "You need not concern yourself with depriving any of my students. Should any of Sakura, Ino, Hinata, or Tenten demonstrate the necessary aptitude and dedication in the future, they too will have the opportunity to forge a contract with Katsuyu. As for the Byakugo Seal," she added, a faint smile playing on her lips, "while it certainly deepens the connection and control, it is not an absolute requirement for establishing a summoning contract with Katsuyu. I myself did not possess it when I first formed our bond. You may sign the scroll without reservation."
Tsunade then offered a final piece of guidance, her expression becoming slightly more stern. "One more thing, while Katsuyu addresses me as 'Tsunade-sama,' you, as a newly contracted summoner, will be expected to address her with the appropriate respect as 'Katsuyu-sama.' I have earned her recognition over many years. You will need to do the same. Until she acknowledges you in kind, respectful address is paramount."
A wave of relief washed over Sasuke, easing the slight tension that had been present. He nodded firmly, his dark eyes now reflecting a burgeoning sense of hope and anticipation.
With a renewed sense of purpose, he made a small incision on his thumb and, with deliberate precision, began to inscribe his name onto the ancient summoning scroll, the crimson ink a stark contrast against the aged parchment.
The path to mastering Senjutsu, a path he had only recently considered, was now unfolding before him, guided by the legendary Slug Princess and her formidable summon.