Both time-traveled characters ended up as villainous henchmen.

Ordinary illusion techniques use chakra to interfere with another person's five senses, thereby confusing and disrupting the enemy.

Advanced illusion techniques are much more complex, not only affecting the five senses but also manipulating the flow of chakra within another person's body.

However, this kind of illusion requires the support of a powerful bloodline limit, such as the Sharingan of the Uchiha clan.

This illusion technique is currently inaccessible to Izumi Nen, let alone learnable.

On the contrary, Orochimaru's records of the Nara clan's shadow techniques opened up new avenues of thought for him.

His Yin Release chakra nature is inherently less effective at exerting mental influence than ordinary Yin Release, so his research on illusion techniques can only serve as a reference.

The Nara clan's Shadow Technique is a secret art that combines Yin Release with their own shadow.

His Yin Release chakra is naturally extremely compatible with his own blood.

After two failed attempts, Izumi Nen successfully controlled his blood, which seeped from the wound and transformed into a small scarlet snake that snaked and coiled around his body.

"However, this method of external deployment doesn't seem to have much practical value in combat."

Izumi Nen pulled the blood back from the wound and muttered to himself.

It goes without saying which is more important to the human body: blood or shadow.

The shadow can be changed and stretched at will, and even if it is destroyed by ninjutsu, it will not have a significant impact on the ninja himself.

If the blood is released externally, he might bleed to death before the enemy is even injured.

Furthermore, after being brought back from outside, it might bring back some bacteria or viruses.

"So it can only remain inside the body, serving as a kind of enhancement technique to improve physical fitness?"

Izumi Nen naturally thought of another manga, Jujutsu Kaisen, specifically the jutsu technique called Crimson Blood Technique.

The Crimson Blood Manipulation Technique is very similar to the blood ninjutsu he is currently developing. In the Jujutsu Kaisen, the human side mainly uses the Crimson Blood Manipulation Technique for physical enhancement. If they really want to use blood attacks, they prepare blood bags in advance.

Unless one masters the reversal technique and can convert their own magical power into blood, it cannot be used for large-scale attacks.

Fortunately, his Yin Release chakra can absorb the blood of others to heal himself. As long as he keeps exchanging injuries and using battle to sustain himself, he will most likely be the one to survive in the end.

"This scene is a bit too inappropriate for children..."

Although a solution was found, that fighting style meant that Izumi Nen had crossed the line and was "eating" people.

This is what he has always tried his best to avoid, and it is also the biggest obsession in the shared memories of He Nian in the Demon Slayer series.

"Forget it, let's continue the research. Besides, the current stage of the blood technique is far from meeting my expectations."

Izumi Nen sighed softly, raised his hand and released two C-rank Water Release ninjutsu, Water Chaos Wave, to wash away the strong stench of blood in the underground training room.

He then turned and left the place.

The initial development of blood-based Yin Release ninjutsu has been completed, taking only one afternoon from start to finish.

The reason it was able to happen so quickly is mainly due to the shared essence of demon life in Demon Slayer.

Izumi already had a foundation, and with just a little guidance, he could succeed.

Although the development results were not entirely satisfactory to Izumi, the effects were significant in other aspects.

After his original instincts were systematically integrated into the ninjutsu system, his efficiency in absorbing and utilizing blood has increased by about three times compared to before.

The self-healing effect was thus enhanced in the same way.

Furthermore, the amount of Yin Release chakra that can be stored in the blood has nearly doubled.

Izumi Nen could even sense that there were some changes deep within his body.

He was not clear about the specifics and needed to undergo a thorough physical examination.

This was also a major reason why he ended his spiritual practice.

Stepping out of the underground training room, Izumi Nen strode towards the room where Orochimaru usually performed physical examinations on him.

The room was equipped with all kinds of advanced medical equipment, comparable to Konoha Hospital.

These were the additional devices Orochimaru added after discovering the value of his Sage Body.

Izumi Nen's immortal body has a far greater efficiency in absorbing and transforming natural energy than the Jugo clan's immortal transformation.

The difference is that the Jugo clan can synthesize Sage Chakra on their own after absorbing natural energy, which Izumi Nen's Sage Body cannot do.

Of course, this also avoids the risk of Izumi Nen being affected by natural energy and becoming insane and distorted.

Orochimaru didn't take this very seriously at first. After all, he initially researched the Cursed Seal because he couldn't train in Sage Mode, and the Cursed Seal was a simplified version of Sage Mode that could be used immediately, even though it was very dangerous.

However, if Izumi Nen's Sage Body wants to synthesize Sage Chakra, he still needs to train on his own. Compared with the convenience and speed of the Cursed Seal, it is naturally inferior.

However, Orochimaru later discovered the true destination of the natural energy that Izumi Nen had absorbed and transformed.

It is not temporarily stored in the body as raw material for synthesizing Sage Chakra, but is completely integrated into every corner of the body, promoting the slow sublimation of one's own life essence.

This is a complete transformation from the inside out! It's not just a temporary boost of power!

This discovery completely ignited Orochimaru's enthusiasm, and he relaxed his demands on Izumi Nen considerably, providing him with basic training resources and ninjutsu scrolls.

Nowadays, the walls of the examination room are covered with a lot of Izumi Nen's physical data from each of his medical checkups.

As time went on, Izumi Nen's physical stats continued to rise, and Orochimaru's smile grew wider.

Izumi Nen simply glanced at the charts and graphs pasted on the wall before activating the device and beginning to examine himself.

Two hours later, the results of all the tests were released.

Regarding physical data, since Orochimaru had not yet experienced space sharing during his last examination, Izumi Nen's physical data has now improved significantly.

However, the data table also accurately reflects his current abnormality.

The powerful activity of blood, and the significantly enhanced circulatory system in the body.

More and denser blood vessels appeared in his body.

This transformation could not possibly escape Orochimaru's notice. If the other party were to examine his blood, his blood-based Yin Release ninjutsu and his ability to devour others' lives and transform them into his own power would surely be discovered.

"This is troublesome. We need to eliminate this abnormal change before Orochimaru returns..."

Fortunately, Orochimaru had only been on a mission for a day or two, so he still had at least a month to research and improve it.

Izumi Nen sat cross-legged on the examination bed, resting his chin on his hand as he pondered.

"If a single chakra nature transformation doesn't work, what about two or more bloodline limits...?"

After a moment of contemplation, Izumi Nen had a new idea.

Bloodline limits are a topic that will never go out of style in the ninja world. All incomprehensible ninjutsu can be explained by bloodline limits.

He might be able to explain his own changes using the special bloodline of a celestial being.

However, the changes in his blood and blood vessels were clearly inconsistent with his previous immortal body style, so he needed to find a new bloodline limit as a reason.

Moreover, after fusing and upgrading to a bloodline limit, he might be able to further eliminate the negative effects of this blood-based Yin Release.

"Yin Release... Bloodline Limit..."

Naturally, Izumi thought of the two Yin Release bloodline clans currently in Konoha: the Uchiha and the Nara.

He needs the blood samples from these two companies as reference material.

However, he wasn't very familiar with the Nara clan, and they were not easily fooled; taking their blood rashly might cause trouble.

On the contrary, the Uchiha side is much easier to deal with.

"Obito, I choose you!"