The Big Sister Next Door, Katsuyu

Natsuki didn't dare compare herself to Tsunade. This wasn't modesty—before Tsunade, every Medical Ninja would feel ashamed of their own inadequacy. In his previous life, Fifth Hokage Tsunade had left Duke with two very deep impressions. The first was that terrifying pair of ominous signs that could make Newton die with his eyes still open. For details, one could refer to all kinds of TXT, JPG, and RMVB files, which contained very thorough descriptions. The second was her Medical Ninjutsu, which allowed her to remain lively and kicking even after being cut in half at the waist.

As the sole woman among the Sannin, Tsunade's mastery of Medical Ninjutsu could be called unmatched in her era, unprecedented and unsurpassed. In the Shinobi World, whether friend or foe, anyone who saw Tsunade would respectfully call her "Lady Tsunade." It was both recognition of her strength and the highest respect for this saintly healer who saved lives and healed the wounded. After the Second Great Ninja War, Tsunade left Konoha without suffering any harassment from enemy shinobi. On the contrary, whenever they learned of her whereabouts, their first thought was to seek her help. This showed just how exceptional her medical skills were.

For now, Duke had no way of coming into contact with such a legendary figure standing at the pinnacle of all Medical Ninja. The other two Sannin who remained in Konoha were also names he had heard but people he had never met. Whenever he thought of that, Duke felt deeply discouraged. Other transmigrators, at his age, were already calling Jiraiya their brother and researching reincarnation techniques with Orochimaru. Some had even successfully won over Tsunade and built vast harems.

Five-year-old Duke was still raising a dog and fighting desperately to make a living, while other transmigrators had already been drinking milk in Tsunade's arms at five. When bored, they would casually guide Minato Namikaze in cultivating the Rasengan and Flying Thunder God to pass the time. The bloody reality told Duke that he was a complete and utter failure, with a long road still ahead before he could succeed.

"Medical Ninjutsu is a category of ninjutsu in which the caster uses chakra to stimulate cells, healing a patient's wounds. Through shape transformation, it can also detoxify or attack." After putting Anko to sleep, Natsuki gave Duke a simple introduction to Medical Ninjutsu, then said solemnly, "Mastering Medical Ninjutsu requires not only precise chakra control, but also extensive theoretical knowledge. For example, the distribution of the body's internal organs, blood vessels, bones, meridians, nerves, and acupoints. This medical knowledge is dry and boring, and it takes a great deal of time and energy to fully understand. There are no shortcuts besides rote memorization. If you can't endure it and give up halfway through, you might as well quit now."

"I won't give up. I'm very talented in medicine!" Duke said confidently. As a medical dog comparable to a lawyer dog, chewing through books was nothing. Besides, it wasn't as if he hadn't memorized all this in his previous life. He was only picking it back up and learning it again. As a top student, he would get through it soon enough. What? You're saying he was only a proctologist, and this wasn't his specialty? Hmph, what did you know about doctors? A proctologist was still a doctor.

"You competitive little brat. I hope you really can do as you say." Natsuki didn't criticize Duke for overestimating himself. In the shinobi world, adults were more inclined to encourage the next generation.

"I always keep my word. That's my ninja way!" Duke borrowed someone's famous line.

"Then let me see just how far you can go!"

Duke's answer pleased Natsuki. After speaking, she stood up, bit her finger, formed five hand seals, pressed her hand against the ground, and shouted, "Summoning Jutsu!"

White smoke spread through the room. When it dispersed, a huge blue-and-white mollusk appeared, wet and slimy all over, roughly two meters long. In his previous life, Duke would have called this kind of shell-less snail a slug. But in the ninja world, she was a famous top-tier summoned beast—Katsuyu.

Duke's mouth fell open. With trembling fingers, he pointed at Katsuyu and gave Natsuki a puzzled look. Could it be that Aunt Natsuki's hidden identity was Tsunade's disciple? Otherwise, how could she possess Tsunade's exclusive summoned beast?

It was no wonder Duke was so shocked. He was no longer a complete novice when it came to shinobi matters, and he knew very well how precious a top-tier summoned beast was. Calling it one in ten thousand wouldn't even begin to describe it. In the Shinobi World, only true disciples inherited top-tier summoned beasts. And it wasn't as though a teacher could simply teach a disciple and have them learn it. If the affinity wasn't enough, or the summoned beast didn't like the look of you, then even if you signed a contract, you still wouldn't be able to summon them. Yes, they were just that willful!

"Long time no see, Lady Katsuyu!" Natsuki said politely, bowing to Katsuyu.

"Natsuki, it has indeed been a long time. I heard you have already given up being a shinobi and become a full-time housewife." Katsuyu's voice was gentle, like the refined big sister next door. Among the Sannin's summoned beasts, she had the best temper. Of course, her Power Level was also the weakest, and she was more outstanding in medical matters.

"I've disappointed you. I met a man I was willing to devote my entire life to," Natsuki said apologetically, though her face was filled with warm happiness.

"Is that so? That's not bad either." Katsuyu nodded, offering both comfort and blessings.

"I called for you this time because of this child. He wants to learn Medical Ninjutsu, so I need to retrieve the medical theory scrolls I stored in Shikkotsu Forest. I'm sorry to trouble you. Duke, hurry up and greet Lady Katsuyu!" Natsuki placed a hand on Duke's head and pushed him down, making him bow.

"Lady Katsuyu..." Duke was still stunned, his body somewhat stiff.

"It's no trouble. They were yours to begin with." As Katsuyu spoke, her boneless body slowly wriggled, and she spat out a huge slimy scroll with the character for "medicine" written on it.

"Thank you, Lady Katsuyu."

"Then goodbye, Natsuki. I hope that the next time you summon me, it will be as a Medical Ninja." After saying that, Katsuyu turned into smoke and returned to the Summoning World.

After seeing Katsuyu off, Natsuki let out a sigh of relief. Once she cleaned the liquid off the scroll, she tossed it to Duke. Holding the scroll, which stood a head taller than he did, Duke was both excited and curious. He hurriedly asked, "That was the summoned beast of Princess Tsunade, one of the Sannin, right? Why does Aunt Natsuki have such an incredible summoned beast? Is Aunt Natsuki a disciple of the Sannin?"

"You know about Lady Katsuyu too? I didn't expect you to have such good judgment," Natsuki said in surprise.

"Ah! I heard about it from Asuma at school." Duke shifted the blame, and Asuma caught it squarely.

"No wonder. But the Hokage's son has far too loose a mouth. Even if it isn't classified information, he shouldn't be spreading it everywhere!" Natsuki suddenly understood, then became a little displeased with Asuma. Poor Asuma had been hit by a stray bullet for no reason.

"Hehe!" Duke laughed awkwardly. Asuma, I won't forget your sacrifice.

"Lady Katsuyu lives in the sacred land of the Summoning World, Shikkotsu Forest, and has a contractual relationship with Lady Tsunade's clan. But I am not Lady Tsunade's disciple." Recalling the past, Natsuki said respectfully, "The reason I was fortunate enough to form a contract with Lady Katsuyu was because, when Konoha Hospital was established, the Medical Ninja system was still incomplete. Everyone's medical skills were too poor, and we couldn't save more people. Moved by this, Lady Tsunade brought out the precious contract scroll and promised that outstanding Medical Ninja could leave their names on the contract. First, it was to encourage everyone. Second, Lady Katsuyu is a rare medical-type summoned beast, and she is a great help to Medical Ninja."

"I want to learn that! I want to learn Summoning Jutsu too!" Duke rolled around on the floor, his eyes misty and pitiful as he began acting cute, looking as if he wouldn't stop until he got what he wanted.

"It's no use. Even if you act cute, you can't." Natsuki was struck right in the heart by his cuteness, but she still shook her head and refused.

"Do I need Lady Tsunade's permission?" Duke guessed. After all, it was the Senju Clan's contract beast, so she would need to approve it.

"That's not it." Natsuki shook her head. "Whether you can successfully sign the contract or not, Lady Tsunade doesn't have the final say. Only Lady Katsuyu's agreement matters. Lady Katsuyu only acknowledges shinobi with powerful Medical Ninjutsu. Otherwise, even if you secretly sign a contract, Lady Katsuyu won't recognize it."

So that was it! Duke suddenly understood. No wonder every shinobi in the original story who had a contract with Katsuyu possessed impressive Medical Ninjutsu. It turned out there were conditions for summoning her. If you didn't meet the standard, she wouldn't even acknowledge you!

"Even so, Konoha Hospital must have many Medical Ninja contracted with Lady Katsuyu, right?" Duke asked curiously. As a top-tier summoned beast and a rare medical type at that, she could fight and heal. If so many people had contracts with her, wouldn't that cheapen her status a little?

"Also, if Lady Tsunade used Summoning Jutsu in battle, only to find that Lady Katsuyu had already been summoned by someone else, wouldn't that be awkward?"

"You don't need to worry about that." Natsuki smiled. "Unlike other summoned beasts, Lady Katsuyu doesn't exist as a species living in groups. In all of Shikkotsu Forest, there is only one complete Katsuyu. Like just now, what I summoned was merely a tiny, insignificant part of Lady Katsuyu's body. Even Lady Tsunade cannot summon the complete Lady Katsuyu, so the situation you described will never happen."

"Besides, Lady Katsuyu has very high standards. Many highly skilled Medical Ninja have been rejected by her. I was only lucky. Back then, aside from Lady Tsunade, only three Medical Ninja in all of Konoha Hospital received Lady Katsuyu's approval." Natsuki revealed a sorrowful expression, and her voice gradually softened. "The other two unfortunately died in the wars of the past few years. On the battlefield, Medical Ninja have an extremely high death rate. The enemy always sees us as their top priority targets..."

Natsuki fell silent as she remembered her former comrades. Duke opened his mouth, but he didn't know how to comfort her. Death was always painful. Shinobi might not fear death, but they could never face it calmly.

"A child your age shouldn't wear such a serious face!" Natsuki came back to herself. Seeing Duke looking a little downcast, she rubbed his head and encouraged him, "If you want Lady Katsuyu's recognition, you first need to become a top Medical Ninja. You need to work hard!"

"Don't worry, Aunt Natsuki! I definitely won't disappoint you." Duke pulled himself together. Death was frightening, so if he didn't want to die, he had to work even harder.

"That's the Duke I know. Children aren't allowed to wear such serious faces!" Natsuki said. "But becoming a Medical Ninja has requirements too. I need to test your chakra nature first."

"?" Duke played dumb. Although he had forgotten many details, he still knew about chakra natures from Naruto: fire, wind, lightning, earth, water, yang, and yin—the seven major natures. Of those, the five basic ones could be tested with chakra paper, which was very convenient.

Medical Ninjutsu should be related to Yang Release... Can chakra paper test that too? Duke was full of doubts.

"Although there is no direct evidence, water and earth are indeed the chakra natures most suited to Medical Ninja. Wind comes next, while fire and lightning are last. Your Water Release is very good, so one of your natures must be water. As for whether you have any other natures..." Natsuki pointed at the clock, covered her mouth, and gave a mischievous smile. "I'll test you after you get home from school this afternoon. But for now... if you don't get to school within three minutes, you'll be standing in the hallway!"

"Ah——"