Naruto: You Call This A Medical Ninja?

After hearing what the Ten-Tails had said, Reiki stood frozen, his mind reeling.

"What?! Is becoming the master of this world supposed to be this casual?" he exclaimed, his tone dripping with disbelief.

"And what exactly are the benefits of becoming the lord of this wasteland? Look at it—just a stump, rocks, and dirt! All I wanted to do was treat you, not inherit a barren job. Don't pile this on me!"

The phantom of the Ten-Tails chuckled, its voice calm but persuasive.

"Becoming the master of this world grants you the power to control the Ten-Tails," it explained. "Moreover, it opens the door to the Path to God."

Reiki raised a skeptical eyebrow. "Path to God? The only path I know is the one back home. Stop trying to sell this to me! Just give me a way to return when necessary, and I'll come back in a month to treat you."

"Very well." The Ten-Tails reached out and grasped Reiki's hand, leaving a unique curse mark on the back of it.

"Inject chakra into this mark, and you'll be able to return here at will," the Ten-Tails said before disappearing.

Reiki stared at the stump and the desolate world before him, muttering with mock pride, "A man acknowledged by the world… What an honor." He sighed and stepped through a rift back to the ninja world.

Upon his return, Reiki found himself at the special training camp. The destroyed battlefield from the previous confrontation was now an active training ground. To his surprise, grass and small plants had begun sprouting in the scarred earth.

"Could this be the residual energy from the First Hokage?" Reiki mused.

Before he could investigate further, a familiar voice interrupted him.

"Finally back. Where have you been all this time?"

Reiki turned to see Black Zetsu emerging from the ground, now merged with White Zetsu.

"Huh? What are you talking about? I just went to handle a quick task." Reiki looked at Black Zetsu quizzically.

"Reiki, you've been gone for three months!" Black Zetsu exclaimed. "Do you even realize how worried everyone has been? If you don't have a good explanation, your teacher will probably kill you."

"Three months?!" Reiki froze in disbelief. "I just took a quick look at the world connected to the Chakra Sacred Tree—how could it have taken so long?"

Before he could process this, Tsunade's arrival snapped him out of his thoughts. Reiki didn't wait for Black Zetsu's further commentary; guilt flooded his mind as he disappeared in a flash to find her.

Outside Tsunade's tent, Reiki hesitated only briefly before entering.

"Teacher, I'm so sorry!" he blurted, kneeling immediately, his head bowed in guilt.

"Reiki?!"

Before she could process his presence, a reflexive blow sent him flying out of the tent. As he tumbled, Reiki caught a fleeting glimpse of… something dazzlingly white.

Embarrassed and refusing to dwell on the memory, Reiki waited until Tsunade's sharp voice called him back.

"Come in!"

This time, Reiki entered cautiously, keeping his gaze low. His cheeks burned with embarrassment, and Tsunade's blush matched his.

"Explain yourself," she said, feigning anger but unable to hide her curiosity. "Where have you been all this time?"

Reiki hesitated. The truth—becoming the master of a barren world for three months—sounded absurd. Instead, he recounted his exploration of the teleportation array and the moon, adding that the long distance had made communication impossible.

"You went to the moon?" Tsunade's surprise replaced her annoyance. "Are you saying Otsutsuki Kaguya is sealed there?"

"Yes," Reiki confirmed. "Black Zetsu helped me gather critical information, and I promised to help him free Kaguya after dealing with Otsutsuki Ishiki. I thought it was the right thing to do."

Tsunade's frown deepened. "So… you haven't freed her yet?"

"Not yet. There are preparations to be made," Reiki admitted. "But I wanted to ensure everything is in place before taking action."

Tsunade leaned forward, her expression serious. "Reiki, I understand your promise to Black Zetsu, but you must think carefully. Once Kaguya is freed, what guarantees do we have that she won't turn against the ninja world?"

Reiki met her gaze, silent for a moment. "I've considered that possibility," he said finally. "But if Kaguya's freedom can prevent the Otsutsuki clan from descending upon us, then it's a risk I'm willing to take. She might be the key to protecting our world."

Tsunade sighed, conflicted. "I trust your judgment, Reiki. But if she shows even a hint of hostility toward the ninja world, promise me you'll act decisively."

"I promise," Reiki said firmly.

As the conversation ended, Tsunade's tension eased slightly, but her concern lingered. The road ahead was fraught with uncertainty, and the ninja world's fate now rested heavily on Reiki's young shoulders.