Start with the Mangekyō and leave Konoha with Madara.

Konoha Village, an unknown underground base.

This is Senju Tobirama's personal research institute.

The facility is located in the core area of ​​Konohagakure Village. It is large in scale and surrounded by dense woods, which not only ensures the secrecy of research work, but also facilitates the development of ninjutsu or various experiments.

Uchiha Kagami followed Tobirama up the stairs and pushed open one secret door after another until he entered an empty laboratory. He had not yet recovered from the shock.

"Teacher... recognized me..."

"He wants me to become Hokage..."

He was a little absent-minded, and Tobirama's earnest expression and comforting words kept replaying in his mind. He just mechanically followed him into the laboratory, so much so that he ignored the scene around him.

"Crack!"

Tobirama turned on the power switch, the circuit was connected, and several rows of bright yellow lights lit up, and the dark laboratory immediately became clearly visible.

Jing finally came to his senses and began to look around subconsciously, with a strong sense of disobedience suddenly rising in his heart.

The first thing that catches your eye is a huge central control console covered with flashing screens and buttons, which are connected to a variety of experimental equipment through sophisticated and complex circuits.

There were special sealing devices used for the development of ninjutsu, chakra analysis instruments, and more than a dozen unnamed biochemical experimental equipment. If it weren't for Tobirama introducing them, he would have thought they were some kind of combat machines.

Dust was floating in the beam of light, and the air was filled with a strange smell mixed with metal and medicine. Rows of refrigerators and filing cabinets passed by on both sides, and through the glass storage cabinets, various test tubes, culture dishes and colorful reagents could be seen.

Jing felt dazzled. He was now in the center of the laboratory.

Going further in, the laboratory is divided into several well-organized areas, including a rest area, a herbal medicine area, a training area... Listening to Tobirama's understated introduction, it seems that each area has different functions.

Jing opened his mouth wide and looked at his teacher in surprise, as if he was meeting him for the first time.

Although the laboratory is equipped with advanced technological equipment, Tobirama still retains some traditional elements, such as the family emblem of the Senju clan, ninja tools, and some ancient scrolls and books hanging on the wall.

This made Jing feel slightly relieved, realizing that he was still in the ninja world.

He was speechless. He had seen too many things today that he could not understand. If he had to sum it up in one sentence, Tobirama's research institute was simply a model of the combination of biology, technology, and ninjutsu.

In a certain cultivation room, he even saw lava. Amid the rolling heat waves, there grew a patch of dark purple plants with branches and twigs spreading out in all directions, like clusters of thorns, with a faint black mist rising from the surface.

The air was twisted and I could feel the heat even through the glass.

"That's the Ghost Bud Grass. Don't be fooled by its plain appearance, but it is the key to our experiment this time." Tobirama noticed his gaze and explained, "The solution in the Ghost Bud Grass plant can easily and effectively reduce the body's rejection reaction. This is a kind of penetration and fusion based on the genetic level..."

Soon, Tobirama brought him to the core of the laboratory. The moment he pushed the door open, Jing was stunned and stood there like a wooden chicken.

What did he see? In a huge tank at the deepest part of the room, the buried First Hokage was quietly soaking in a dark green solution, his eyes closed, his face peaceful, his long black hair spread out like seaweed.

There was a thick stack of experimental materials on the workbench at the side, and the walls were covered with various charts and data. It was obvious that a certain research had been carried out to a certain extent.

"Sense! (Teacher!)" Jing opened his eyes wide and pointed at the glass tank in the distance with trembling voice, "This is..."

Tobirama sighed softly, "It takes strength to become a Hokage, but your current strength mainly comes from the Mangekyō Sharingan. Once you go blind, your strength will drop instantly."

"Your intelligence reminded me that if I could transfer the vitality contained in my brother's cells to you, I might be able to rely on the self-healing factor to continuously repair the optic nerve and avoid the risk of blindness..."

Listening to Tobirama's story, Jing still found it unbelievable, "Teacher can even do such a thing?"

"The question is not whether I can do it, but whether you can accept it?" Tobirama said calmly: "I can't guarantee that the experiment will succeed. If it fails, your life and Konoha will perish together."

"It seems that the teacher has handed the village over to me in disguise."

Jing took a deep breath and said, "Come on, as long as I can win this war and protect more companions, I am not afraid of failure!"

He himself is the only one who knows his physical condition best. Every time he uses the Mangekyō Sharingan's eye technique, both his vision and physical strength are reduced day by day.

He didn't know how long he could hold on, three months? One month? If this continued, he would eventually become completely blind.

Tobirama opened the refrigerator, and as the cold air gushed out, he took out a small bottle of golden solution as if it were a treasure.

The test tube shook, and under the light, layers of light golden ripples appeared.

"This is the genetic fluid that I spent several weeks extracting from my brother's cells." Tobirama held the test tube carefully, "Our ultimate goal is to inject it into your body, fuse it with cells all over your body, regenerate your genes, and completely inherit his power."

Jing's pupils contracted unconsciously. He felt the vigorous vitality in this small bottle of solution. The pure life force was as strong as the scorching sun.

He even had a hunch that if he dripped the solution into the soil, a towering tree would instantly sprout from the ground! If he sprinkled it all over, a dense forest would instantly form!

He really couldn't imagine what terrible things would happen if he injected this bottle of solution into his body now...

Either be burned to ashes, or become a tree man...

"Don't worry, certainly not now."

Tobirama returned the gene fluid to the refrigerator and locked the doors. "In the next three days, I will also extract your gene fluid from you, analyze and compare the differences, and then use a special fusion agent to try to fuse the two..."

"By constantly adjusting and tweaking the concentration of the gene fluid, until it is assimilated into the one that best suits you..."

"After all samples are perfectly integrated, we can start injecting the gene fluid."

"This is destined to be a long process, and we may have to endure countless failures..."

Tobirama's eyes pierced through his, and his tone was full of trust and determination, "No matter what the final result is, I, and the entire Konoha Village, will bet everything on you."

Jing nodded solemnly.

"First, I need to check your current physical condition and measure your current physical fitness in all aspects..."

Three days later, Tobirama had a light red solution in his hand.