Both time-traveled characters ended up as villainous henchmen.

Underground training room.

The room, which was originally flat and spacious with only some training equipment, is now filled with all sorts of bottles and jars.

There is plain water, plant juice, and prepared medicinal liquid.

It even contains a considerable amount of ninja blood, as well as the blood of animals and summoned beasts.

At this moment, all these various liquids were placed beside Izumi Nen.

Izumi Nen calmly looked at the bottles and jars around him, while slowly mobilizing the chakra of his newly synthesized Yin Release bloodline limit—Ming Shui.

As the hand seals changed, he spat out a dark gray liquid from his mouth.

Immediately afterwards, under his control, the dark water split into more than thirty thin streams, flowing into various containers placed beside him.

In an instant, a strange sense of fusion and connection emanated from the different liquids in each container.

Like all rivers flowing into the sea, everything was brought under his control.

As if by instinct, with a thought, all kinds of liquids were absorbed and devoured by the Netherwater he released.

All kinds of substances in different liquids, whether nutrients, rare chakra, or even more mysterious life force, were completely absorbed into the gray-black dark water.

At this moment, the color of the Netherwater became even darker, and its aura became even more obscure.

However, in Izumi Nen's perception, it was a completely different scene.

Silent, profound, and all-encompassing.

After silently sensing it for a while, he changed his mind again, and the Netherwater, which contained the essence of various liquids, was successfully retrieved.

Instead of swallowing it directly, it turned into a thin layer of liquid that covered the surface of his body.

At the same time, the various essential substances contained in the Netherwater, after being filtered by the Netherwater, transformed into a rich and special Yin Release chakra, which was injected into his body.

It enters the bloodstream and flows to all parts of the body.

As blood continued to circulate in his body, the wound on his arm that he had made beforehand healed completely almost instantly.

The remaining Yin Release chakra that had not been consumed did not dissipate but instead merged directly into his blood, lying dormant deep within his body and accumulating there, waiting for the next injury to resurface.

The amount of chakra he can accumulate is about three times his current total chakra.

Of course, this portion of chakra is not only used to heal injuries, but can also be used to release the Yin Release ninjutsu.

After calming down the dense Yin Release chakra within his body, Izumi Nen stood up and slowly moved around, feeling the abundant power within him.

The Yin Release chakra of the Nether Water that lies dormant within him also possesses the characteristics of the original Dark Blood Yin Release.

Physical fitness can be significantly improved by controlling blood flow and the composition of substances in the blood.

Even as the Yin Release chakra of the Nether Water entered his bloodstream, his long-dormant Sage Body was also undergoing a subtle transformation.

The original conflict with his own Yang Escape technique has completely disappeared, leaving only a sense of seamless integration.

Izumi Nen had never felt so good; his long-suppressed emotions were released at this moment.

After cheering for a while, he quickly tidied up the training room and then headed to the medical examination room.

He wants to conduct a detailed and comprehensive examination of the current Netherworld Yin Escape Technique and the Immortal Body.

And so another afternoon passed.

Inside the examination room, Izumi Nian held the test report on the Netherworld Water Yin Escape and his current immortal body, comparing it with his previous physical and mental experiences.

First is the Yin Escape Technique of the Underworld.

It possesses a powerful ability to devour, absorb, and corrode all kinds of liquid substances, and can convert all absorbed substances into Yin Release Chakra to heal injuries.

Furthermore, the Yin Release chakra of the Dark Water will further enhance his physical attributes after it is integrated into his blood.

He can even selectively strengthen parts of the body by controlling the growth of blood vessels.

Even growing blood vessels outside the body to form a layer of blood armor, or condensing them into weapons, is possible.

However, doing so would accelerate the depletion of the Yin Release Chakra stored in his blood.

When his Yin Release chakra is depleted, he can choose to absorb the essence of various liquid substances to recover, or he can synthesize and refine it from physical and mental energy, just like a normal ninja recovers chakra.

The biggest limitation restricting the effectiveness of Izumi Nenmei's Yin Escape technique—the source problem—has been successfully resolved.

Furthermore, the original flaws of Demon Slayer He Nian as a cannibal demon... no longer exist.

Whether it was the cruel and bloodthirsty thoughts in his heart, or the restraining relationship between Yang Release chakra and his special Yin Release, all of them were now dissolved by the Nether Water.

The water in the underworld is so calm that it is almost deathly still, which can help him stabilize his emotions and prevent him from being easily swayed by them.

Ordinary Yang Release no longer has a restraining effect on Dark Water. At least a special Yang Release bloodline limit is required, such as a bloodline limit that combines Yang Release and Fire Release, or even a higher-level special Yang Release, to be effective.

This advanced Yang Escape technique is far more powerful than before, capable of producing a devastating effect against the Nether Water.

Only when the amount of chakra from a high-level Yang Release exceeds that of the Nether Water released by Izumi Nen can it have a certain restraining effect on it.

It may weaken or reduce the devouring ability of the Netherwater, or slow down the healing speed of Izumi Nen's injuries, so that it will no longer collapse at the slightest touch as before.

Moreover, as Izumi Nen shares more power, there are probably very few people in the ninja world with more chakra than him.

Therefore, this point can be completely ignored.

Regarding the immortal body.

Its original ability to spontaneously absorb natural energy was enhanced after the last sharing of power in the black mist space, roughly five times the increase it had when Izumi Nen first awakened his immortal body.

It seems like a big improvement, but because he originally absorbed very little natural energy, even if he improved, the overall improvement wasn't much.

Although the appearance of the Netherworld Water Yin Escape did not bring about obvious changes to the immortal body, Izumi Nen could sense that his immortal body was undergoing a profound transformation.

It seems to be because it shares some of Pikachu's evolutionary power as a Pokémon.

His current immortal body is undergoing a slow evolution.

Izumi had a premonition that the evolved immortal body would bring him an even greater surprise.

However, the current rate of evolution is too slow.

Fortunately, after a series of detailed examinations and his deep perception, he has grasped the evolutionary trajectory of the immortal body at this moment.

The fusion of Yin and Yang.

In the Naruto world, Yin Release represents secret techniques that originate from spiritual energy, while Yang Release represents physical energy.

Yin Dun can create form without being visible, while Yang Dun can infuse life into form.

The combination of Yin and Yang is the art of creating all things from nothing and giving them life.

The nine tailed beasts in the ninja world were created by the Sage of Six Paths using Yin-Yang Release.

Without a doubt, once his immortal body evolves to the level of Yin-Yang Release, his strength will experience a leap forward!

Therefore, Izumi Nen's next goal is clear: to accelerate the evolution of his immortal body through other auxiliary means.

"Sealing techniques, chakra pathways, circulatory system..."

Izumi Nen muttered to himself, his eyes growing brighter, as he began to form a vague idea!