Yū's Laboratory

In a clearing in the woods at the edge of the village, the three of them—Yu, Sasuke, and Naruto—had a place they often went.

The trees and ground around their usual spot were covered in signs of battle, all of them left by Sasuke and Naruto.

Their 103rd battle ended when a Shuriken landed against Naruto's neck.

At that moment, Yu stepped forward as the referee.

"The 103rd battle is over. The winner is Sasuke."

Yu raised Sasuke's hand as he spoke.

Naruto plopped down on the ground, fuming. He'd practiced Shurikenjutsu as hard as he could, but he was still far behind Sasuke.

Ever since Naruto had beaten Sasuke in close-quarters Taijutsu last time, Sasuke had stopped fighting him up close so often. Instead, he'd started using Naruto as a target to practice his Shurikenjutsu.

Naruto was completely caught off guard.

"Sasuke, do you dare fight me fair and square without using Shuriken?" Naruto challenged him.

But Sasuke only shot Naruto a look and didn't take the bait.

"Hmph! A dead last will always be a dead last."

Sasuke even took the opportunity to taunt him.

Naruto was physically stronger than Sasuke, and his recovery was downright monstrous. Even with the best medicine, Sasuke couldn't recover as quickly as Naruto. That made close-quarters fighting a losing proposition: after one battle, Sasuke needed several days to recover, while Naruto was back in top form the very next day.

So Sasuke had gotten wise. He generally avoided close-quarters fights with Naruto. All he cared about was winning; how he won didn't matter.

"Yu, you tell him what's fair. Sasuke's a coward if he won't even accept this kind of challenge." Unable to do anything but rage at Sasuke's attitude, Naruto turned to his good friend Yu.

But Yu could only shake his head helplessly, showing that he couldn't make Sasuke accept the challenge either.

"Hmph!"

Sasuke snorted and curled his lips into a smug smile. How could his little brother ever "betray" him?

The three of them parted ways after sunset. When Yu got home, he ate with Sasuke as usual, then went to the laboratory once they'd finished.

"Yu, how's your research coming along?" Sasuke asked him something he rarely brought up.

"It's going well. I've already had a few results."

Yu answered without giving it much thought.

"Mm!"

Sasuke nodded pensively. He clearly had something else to say, but was struggling with how to bring it up.

Even after they finished eating, Sasuke still hadn't said anything.

Yu noticed.

"Sasuke, would you like to visit my laboratory?" Yu invited him. Sasuke was someone he could trust, and there were things he could share with him.

That was what Sasuke had wanted to ask. He really wanted to know what Yu had been doing for the past two years. He'd never asked, and Yu had never told him, so the question had remained unanswered until now.

But since he spent every day with Yu, Sasuke had noticed that something about him had changed lately. He seemed much more confident, as if the pressure weighing on his heart had finally lifted and he could breathe again.

So Sasuke had been looking for a chance to find out what had happened to Yu. It was because he cared about him.

Although the laboratory had been built by outsiders, Yu had modified it over the past two years. After all, there were people and things he couldn't afford to let his guard down around.

"Sasuke, make sure you follow in my footsteps when we go in," Yu told him.

"Got it."

Sasuke replied.

He didn't know how much good traps would do against a ninja, but they were better than nothing.

With Yu leading the way, Sasuke entered the laboratory without difficulty.

The spacious laboratory had changed completely over the past two years. Every inch of it was being put to use, and Yu had even expanded it.

"Mm-mo... mm-mo..."

As soon as Yu and Sasuke stepped into the laboratory, a huge creature blocked their way.

Over the past two years, Number Two had grown larger and larger. Its body was now three meters in diameter, and its intelligence had grown as well. Number Two now had the mind of an ordinary ten-year-old child. It was a true Slime life-form.

Over the past two years, Yu had cultivated more than two hundred Slimes. In the end, only three of them had developed self-awareness like Number Two.

"What is that?"

Sasuke asked Yu when he saw Number Two. This jelly-like creature was completely beyond his understanding.

"It's called Ar Two. It's a Slime, and one of my Summoning Beasts," Yu explained.

"A Slime? It looks so strange." Sasuke studied the Slime. He didn't know what a Slime was, but he did understand Summoning Beasts. He even reached out and ran his hand over Ar Two's body. It felt quite nice and smooth.

"Feel free to look around, Sasuke. There's nothing dangerous here. Oh, I also have another Slime Summoning Beast called Red Cat. It has a rather odd personality and loves challenging other creatures, but its attacks are weak, so it's not dangerous," Yu told Sasuke.

"I'm going to get something. I'll be right back."

After hearing Yu's explanation, Sasuke nodded and began to explore the laboratory, curious.

The laboratory was full of glassware. Glass boxes, bottles, and domes were everywhere, and each one contained a Slime. The Slimes came in all sorts of strange shapes and a wide range of colors.

A few Slimes were inside glass tubes, their bodies radiating an intense light that illuminated the laboratory.

There were many wondrous creatures in this world. For the past two years, Yu had been collecting tissue samples from all kinds of creatures. The incredible variety had made him realize that the world of Naruto wasn't limited to what the anime depicted. There were still countless mysteries to uncover.

Yu had named the glowing Slimes Sun Slimes. They had been created by combining Slimes with the bloodline of a kind of ocean fish that could emit light.

In fact, wasn't this kind of fish simply blessed with a different kind of Kekkei Genkai? It was just that ordinary fish couldn't refine Chakra.

But Slimes could. Even when the Slimes he cultivated lacked self-awareness, Yu could still control them and make them refine Chakra. Their output was very low, but it was enough to activate and enhance their abilities.

The Sunlight Slimes inside the glass tubes had gained the ability to glow dozens of times more brightly with just a little Chakra. Though the Sunlight Slimes could only glow, they had opened up an entirely new world for Yu. He was constantly growing.

Besides the Sunlight Slimes, the laboratory also contained dozens of other varieties, including Lightning Slimes, Venom Slimes, Hairy Slimes, and Floating Slimes.

Sasuke was dazzled. He'd never imagined Yu's laboratory would look like this.