Susanoo vs. Flame Demon Descent!!!

Issui smiled and said to Itachi, "To be honest, I have to thank you for your gift. From now on, I can use this black flame Amaterasu at will. The only thing I need to do is activate the second stage of the Eye of Heaven and consume more Chakra than a normal Fire Style. You are completely countered by me. Eye of Heaven VS Sharingan, the first match, the Eye of Heaven wins."

What? He can just use Amaterasu like that? Impossible! Even using the Mangekyō Sharingan to unleash Amaterasu would damage my eyesight. Doesn't he have any problems at all?

As if sensing Itachi's question, Issui continued, "You're asking why using Amaterasu, a flame, causes you some harm, while I can use it freely without any restraint."

Itachi frowned and said, "That's true. I don't believe such a claim. Powerful techniques often have various limitations, and the user will also be harmed after using them."

Issui nodded. "What you said is correct, but you overlooked one problem."

Itachi asked, "What's the problem? Could you explain it?"

Issui hummed in agreement and said, "This is the root of Kekkei Genkai. Judging from your Sharingan, these are eyes that see through the world but are cursed. The key is the curse. If the curse is lifted, any technique you use shouldn't affect your eyes at all; it would only waste a little Chakra and spiritual energy. Therefore, there should be a higher stage above your Mangekyō Sharingan. I'll tentatively call it the Eternal Mangekyō Sharingan."

Itachi was startled. He actually knew or deduced the existence of the Eternal Mangekyō Sharingan. So that's how it is.

Issui Itachi understood, Yishui continued, "Now let's look at my Eye of Heaven. From our clan's secret scriptures, we know that the first stage of the Eye of Heaven includes both protective and offensive Secret Technique, making it a Secret Technique entity of offense and defense. The Eye of Heaven isn't particularly powerful; each stage of the Heaven Clan's Eye of Heaven only awakens one Secret Technique, either offensive or defensive. However, I am a genius at cultivating the Eye of Heaven, you know? With each advancement to a new stage, I awaken all the Secret Technique of that stage. The original weaknesses become completely useless in me. I am an all-around being, combining offense and defense. It's said that the final stage of the Eye of Heaven grants its possessor immortality, but historically, no Heaven Clan has ever reached this level, not even our ancestor—the fallen god. Alright, enough said, do you understand now?"

Uchiha Itachi was a genius at cultivating the Sharingan, Issui Kanna was a genius at cultivating the Eye of Heaven. So, who was the greater genius?

After battling Issui for half a day, Itachi finally realized how formidable his opponent was. Could the Eye of Heaven be a counter to the Sharingan? No, there are no invincible Kekkei Genkai; only the user of Kekkei Genkai distinguishes Yamato weakness. Even the strongest Kekkei Genkai has its weaknesses, and even the Kekkei Genkai has its advantages. Sigh, it seems he underestimated his Kekkei Genkai. But this monstrous technique also has its flaws, right? Time. Only time is its constraint. The biggest weakness of this powerful technique is time.

Issui Uchiha Itachi gradually calmed down, Yishui was secretly alarmed. To remain calm even when faced with such a troublesome Secret Technique, and to consider its inherent flaws—this was the most terrifying kind of ninja. He displayed a clear mind at all times, truly deserving of the title "wise ninja." Wisdom represents a ninja's knowledge and IQ. Having been a double agent since the age of 11, he possessed a deeper understanding of the world, life, and values than most, and an awareness of life beyond the ordinary. Furthermore, he had continuously improved his combat intelligence during his years of brutal life as a rogue missing-nin. Indeed, he was a formidable opponent and a truly terrifying presence.

Itachi's eyes gleamed. "Your Secret Technique's time is almost up!"

Sure enough, he saw through it, and after being intimidated by his own words, he immediately came to his senses. Speaking of which, Itachi is truly a genius. He's probably only 17 years old now, while I'm over 30 years old in my two lifetimes combined. With the knowledge from both worlds, I only have this kind of power now, mostly thanks to my abnormal Kekkei Genkai. Itachi is actually much stronger than me. He's a true genius.

"Smack!"

Issui's body gradually returned to its original physical form. It seems the time for using the Flame Body has come to an end; the cooldown period is a full minute.

Itachi, with an expression of certainty, said, "My guess was right. Your technique does indeed have a time limit. How will you fight next?"

Issui said calmly, "Is that so? Then try this Secret Technique: Eye of Heaven - White — Sealing Domain!"

Sealing Domain... wait, the flow of Chakra within my body is restricted. I 'Kakuzu mention this ability before; it's even stronger now, limiting even the use of the Three Basic Techniques. It seems I can't dodge it; I'll have to attack with my true form. But how wide is this domain?

Seeing Itachi's question, Issui said, "You're wondering about the size of this technique's area of effect, right? Well, I'll tell you then. Its effective range is a circular area with a radius of thirty meters centered on me. Got it? Even if you knew, it wouldn't matter. If you launch a Ninjutsu attack from 30 meters away, even if it hits me, it won't have any effect. Moreover, the 30-meter distance greatly increases the enemy's reaction time, and you have to be careful to leave my area of effect at all times. On the contrary, I don't have these concerns. However, you can use Secret Technique, Taijutsu, and Genjutsu. You are a ninja who mainly relies on skill, so your Taijutsu isn't strong, Genjutsu is useless against me. Only Secret Technique, that is, your Dōjutsu, will work."

Itachi nodded. "Yeah, I see. Ordinary ninjas are really afraid. This kind of Chakra- restricting technique is like creating your own world and setting your own rules. I have no restrictions, but others can't use Ninjutsu. Ninjas who don't know Taijutsu and aren't Kekkei Genkai will simply die or get injured if they encounter you. And Genjutsu has no effect on you. Such restrictions are really harsh."

"Enough talk, let's fight! Wasting time is wasting Chakra! Sheep-Noon-Snake-Dragon-Rat-Ox-Tiger, Fire Style: Fire Dragon Flame Bullet!!!" Issui launched an attack directly at Itachi.

A massive fireball hurtled toward Itachi. He hastily rolled away, dodging the attack, but his black trench coat embroidered with red clouds was burned with several holes, his face was covered in dirt, and his body was scorching hot from the Fire Style. He was in a truly sorry state.

Itachi stood up expressionlessly and said, "Your Secret Technique consumes a lot of Chakra, doesn't it? That's a flaw, isn't it? That's why you were in such a hurry to attack. It seems you won't be leaving today without showing some powerful moves. Well then, let me show you the flawless divine power of the Mangekyō Sharingan. This is a hidden yet powerful Dōjutsu mastered after Tsukuyomi, representing the 'spiritual world and darkness,' and Amaterasu, representing Amaterasu 'material world and light' —Susanoo!!!"

Itachi's body was surrounded by a huge humanoid skeleton. Gradually, the individual skeletons of the giant humanoid became visible, and its immense power proclaimed to the world that it was an invincible war god. It held a shield in its left hand and a giant sword in its right hand, looking incredibly cool and arrogant.

Issui: I'll join in too! Let's all have a contest. "Eye of Heaven: Flame, the Flame Demon Descent!!!"

A colossal fire giant attached itself to Issui's body, and the flames gradually took shape, eventually forming Flame Demon God over thirty meters tall. Within half a meter of the Flame Demon God, everything was burned to ashes, and the ground beneath its feet was scorched black and shiny, with tiny cracks of magma appearing from time to time, as if the Demon God were alive, its demonic flames raging fiercely!

Itachi observed the Issui of fire giants with great interest. Another fated showdown, huh? Last time, my Amaterasu lost; what about this time?

In terms of appearance, Itachi's Bone God of War is much smaller than the Issui Flame Demon God of War. After all, the Flame Demon God is over thirty meters tall, which is not something that can be achieved easily. Compared to the Flame Demon God of War, Itachi's Bone God of War looks like a child. However, Itachi's Susanoo's three sacred treasures are not to be underestimated. Although they are not physical sacred treasures, they are still extremely powerful.

Issui didn't stand there in a daze; instead, he walked straight toward Uchiha Itachi Flame Demon God, leaving a trail of destruction in his wake.

"Flame Demon Purgatory Slash!!!"

With Issui single grasp, a massive flaming blade appeared in the Flame Demon God's hand, fiercely slashing towards Itachi's skeletal warrior form. The wind pressure from the strike caused a violent gust of wind to blow around Itachi, snapping some small trees in half.

Itachi's expression changed in surprise. He raised his left hand, and a huge shield covered the skeletal war god's body. The flaming blade was bounced back as soon as it touched the shield, but it quickly fell down again, only to be bounced back again, before continuing its slash.

Itachi's Yata Mirror is a formless divine shield that can deflect all attacks. It possesses all nature transformations, changing its own attribute according to the attack's attribute to nullify it. When used in conjunction with the Totsuka Blade, Itachi can achieve a near-invincible state of offense and defense. However, a problem arises: if the force of the attack exceeds its tolerance, can it continue to defend?

Issui's Flame Blade is a slashing attack that locks onto the enemy upon activation, making it unavoidable. The key point here is that it is unavoidable, meaning that Itachi cannot escape Issui's attack and can only defend. However, it will only disappear when the Flame Blade's power dissipates. As long as its power is not exhausted, it will shamelessly continue until its power is completely depleted.

Itachi's health was very poor, and the aftereffects of using Susanoo were gradually appearing. Blood began to flow from Itachi's eyes. Today, he had used the three Mangekyō Sharingan Dōjutsu — Tsukuyomi, Amaterasu, and Susanoo— in succession. His body was gradually weakening, and his vision was becoming increasingly blurry. This was the cursed power of the non- Eternal Mangekyō Sharingan. Only by obtaining the eyes of a brother of the same type could this problem be overcome. Apart from that, there was no other known method.