The Land of Rivers, Konoha Ninja Army Camp.
Dosuke was concentrating intensely on blending the base solution for the medical solution in his tent.
Suddenly, his hands trembled.
"Tch, another failure." He set the test tube down.
Dosuke formed a hand seal. "Ninja Art: Summoning Technique."
Poof!
A small plume of smoke cleared to reveal a palm-sized slug.
"Charan, what is it?" Dosuke asked curiously, holding the small slug in his palm. He had felt the psychic call from the Shikkotsu Forest slugs a moment ago, and the distraction had ruined his latest batch.
"Dosuke-sama, Tsunade-sama has summoned you. She wishes to speak with you in the Shikkotsu Forest!" Charan's childish voice spoke directly into Dosuke's mind.
Charan was a palm-sized slug. Despite its small stature, it was incredibly fast—a slug specialized for communication. It could transmit voices directly into a person's mind and relay messages between individuals within a certain range.
"Tsunade-sensei? Did she say what it was about?" Dosuke asked.
"This… Charan isn't sure! But Dosuke-sama, please come to the Shikkotsu Forest quickly! Tsunade-sama is waiting!"
With that, Charan vanished in another puff of smoke, returning to the forest.
"It must be about the medical solution," Dosuke mused. Orochimaru had sent the full experimental report back to the village; he knew that. This was likely the reason for Tsunade's summons.
"Ninja Art: Reverse Summoning!"
As the smoke dissipated, Dosuke vanished from the camp.
---
The Shikkotsu Forest was, as ever, a landscape of pale stone and quiet desolation. Yet, the sight of countless tiny slugs crawling over the slopes filled him with a profound sense of peace.
As soon as Dosuke landed, he spotted Chiring not far away, standing upright and spinning in dizzying circles.
"Chiring!" he called out.
THUD!
With a loud noise, Chiring, who had been spinning just a moment before, fell flat on the ground, squishing several smaller slugs that hadn't scrambled away in time. Fortunately, slugs were mollusks; otherwise, Chiring's crash would have been a massacre.
"(((φ(◎ロ◎;)φ))) Who's calling me?!" Chiring yelled, its rear end facing Dosuke as it shouted in the opposite direction.
"This idiot…" Dosuke put a hand to his forehead.
A flash of blue chakra lit up at his feet as he leaped directly onto Chiring's head.
"Chiring! Do you know where Tsunade-sensei is? Take me to her!"
"Oh! It's Dosuke-sama! Tsunade-sama is with the Great Sage! I'll take you!" Chiring declared, then began slithering forward, its body still wobbling unsteadily from its earlier spins.
"Chiring, slow down!" Dosuke pleaded, holding on as the giant slug weaved erratically.
Chiring, still seeing stars, barreled toward the location of the Slug Sage and Tsunade. After a wild ride that felt like a triple-loop rollercoaster, it finally skidded to a halt and collapsed.
Dosuke, who had been clinging for dear life, jumped off, vowing never to ride a dizzy Chiring again.
"My, my, Chiring, you silly girl," came the ethereal, gentle voice of the Slug Sage. Without any visible movement from the Great Sage, Chiring's entire body was suddenly launched away into the distance.
A fading "Aaaaaaaaaah!" echoed through the air.
"Little Dosuke, it has been a while," the Slug Sage's voice was as healing as ever.
Hearing it, Dosuke felt the tension leave his body. "Great Sage, where is Tsunade-sensei?"
"Right behind you."
He turned. In his haste to dismount, he hadn't noticed Tsunade relaxing nearby. She was reclining on a chair, gently swaying, with a pot of hot tea beside her.
Dosuke looked at her in surprise. "Sensei, since when do you drink tea?"
"Hah? What's with that look? Can't I drink tea?"
BONK!
Tsunade's brow furrowed slightly as she delivered a loving "Iron Fist" knuckle to Dosuke's head.
"I was wrong!" Dosuke yelped, clutching his skull. "Sensei, why did you call for me this time?"
At the question, Tsunade's expression grew serious. "I read the report Orochimaru sent from the front. I didn't think you'd actually succeed with your research! The old Third Hokage was shocked. You've really made your teacher proud!" Her tone was stern for the first half, but by the end, her whole face had broken into a wide, crescent-eyed grin. She laughed heartily, pulling Dosuke into a headlock under her arm.
Dosuke, still dizzy, was deprived of oxygen. His eyes rolled back, and his arms went limp.
"Sensei… sensei…" he managed to gasp before falling silent.
"Little Tsunade… I think Dosuke has fainted," the Slug Sage observed gently, noting the white foam beginning to form at the corner of Dosuke's mouth.
---
An hour later.
Tsunade watched as Dosuke continued to rub his neck. "Alright, boy, that's enough. I'm a medical-nin too, you know. I can tell when you're actually hurt."
"Fine, fine," Dosuke said, shrinking back slightly as Tsunade raised a threatening fist. "What did you want to talk about, Sensei?"
"Dosuke, what's the current production capacity for the medical solution? Can it be increased?" Tsunade asked, getting straight to the point.
"Sensei, I can produce about a dozen vials a day. But the shelf life is only about three days," Dosuke explained, his own frustration evident. "Sealing the healing chakra can be done by other medical-nin. The bottleneck is me blending the base solution. My maximum is about twenty vials per day."
"I see. Well, let me give it a try," Tsunade said. They were in the Shikkotsu Forest, after all, with all the necessary materials at hand. Both were masters of medical ninjutsu.
No sooner said than done. Under the watchful eye of the Slug Sage, the two got to work.
---
Two hours later.
"Ugh! I give up, I give up!" Tsunade glared at the few test tubes in front of her.
It was too difficult! She had assumed her own medical skills would be more than sufficient to master this process. Reality had slapped that assumption hard.
She took a long, deep look at her disciple sitting across from her. The level of chakra coordination and precise control required was immense. If it was this challenging for her, it would be nearly impossible for any other medical-nin in Konoha, let alone the wider ninja world.
Calculated this way, aside from Dosuke himself, it was unlikely anyone else could achieve the mass production of the medical solution.
Seeing Tsunade fall into a heavy silence, Dosuke felt too awkward to say anything. He, of all people, knew the sheer difficulty of harmonizing the solution's components.
It seemed, for now, the medical solution would remain a precious resource, likely reserved only for elite shinobi like jōnin.