Susanoo

No matter how the Uchiha clan reacted, Shisui could hardly wait to leave the clan grounds. He headed to the forest north of the village.

"Fire Style: Phoenix Sage Flower Nail Crimson."

"Fire Style: Great Dragon Fire Technique."

"Fire Style: Great Fireball Technique."

Shisui Uchiha discovered that with the boost from his Mangekyō Sharingan, his ninjutsu were far more powerful and faster than they had been in his previous life.

He suspected this enhancement was related to the fact that his left eye's ability in this life, "Yamata," had replaced "Kotoamatsukami."

It wasn't as outrageous as the Mangekyō ability "Kagutsuchi," but it still made the cost of using the Mangekyō Sharingan worthwhile.

"It's not just my ninjutsu that's been enhanced. My vision, ability to track movement, and physical strength have all improved considerably. No wonder they call it the Uchiha's strongest eyes."

Shisui had awakened the Mangekyō Sharingan in his previous life, too. But back then, to avoid emboldening the clan's rebels, he had constantly restrained himself from using it.

When he finally decided to use "Kotoamatsukami," Shimura Danzō had stolen his right eye.

In this life, Shisui had the chance to carefully experience everything the Mangekyō Sharingan had to offer.

"Next, it's time to try that technique—the ultimate power of the Mangekyō."

"I wonder if it'll be any different from how it was in my previous life."

That's right. Shisui Uchiha was about to use the supreme ocular technique housed within the Mangekyō Sharingan: Susanoo.

"Susanoo."

For Shisui, who had once awakened Susanoo with only one eye, activating it with both Mangekyō Sharingan was as easy as breathing.

As the Mangekyō in Shisui's eyes spun faster, a great mass of dark green chakra began gathering around his body, forming enormous ribs and arms that shielded most of him.

This was Susanoo's initial form.

Next, even more dark green chakra gathered into additional bones. Susanoo continued to grow until it had become a towering green skeleton with a humanoid upper body.

"This isn't enough." Shisui could feel that this form was nowhere near his limit, so he poured in more chakra.

Bolstered by the immense chakra, the enormous skeletal Susanoo grew taller and taller. Veins and tendons appeared along its bones, and its chakra condensed into flesh. Finally, a cloak-like layer of chakra covered it, and a spiral sword formed in its right hand.

Shisui's Susanoo had skipped the First Form and reached the level of the Second Form.

In his previous life, Shisui had used the Mangekyō in his left eye to activate this form, driving back Danzo and his Root Division subordinates.

In this state, Shisui's Susanoo had already gained a signature technique: "Susanoo: Yasaka Magatama."

When activated, it opened Susanoo's breastplate and fired countless green chakra arrows from its center to attack at long range.

Even now, Shisui still felt fine.

"Neither eye is under too much strain, and I still have plenty of chakra. Let's see where my current limit is."

"Third Form, activate!"

This time, Shisui held nothing back. He summoned all the chakra in his body and sent it surging into the Susanoo behind him.

The distinctive Crow Tengu Helmet spread over Susanoo's body, greatly enhancing its defense. The Susanoo towered dozens of meters into the air.

At this point, Shisui was nearing his limit.

His eyes weren't bleeding, but the aching pain in them warned him that he couldn't push them any further.

As for the Fourth Form, forcing it would only cause irreversible damage to his eyes.

Without the Eternal Mangekyō Sharingan, he also lacked the ocular power and chakra to stabilize Susanoo's Fourth Form.

"Phew."

Shisui took a deep breath and began controlling Susanoo in its Fourth Form.

The enormous spiral sword spun rapidly. The wind it stirred alone sent the surrounding trees swaying wildly and kicked up clouds of dust.

"Pierce."

Susanoo thrust the spiral sword in its hand at a small mountain. Its sharp blade instantly sank into the rock.

As the blade continued to spin, the sword became like a gigantic drill, boring relentlessly into the mountain and wreaking havoc inside.

Sand and chunks of rock flew in every direction, but Susanoo shielded Shisui from them until the sword had pierced straight through the mountain.

"Not bad for offense, especially when it comes to breaking through a single point. It'd be perfect for cracking an enemy's turtle shell."

Shisui then tried several other attack methods with Susanoo, until his eyes began to ache and throb again.

"Susanoo: Release."

Having achieved his goal, Shisui immediately dispelled Susanoo's Third Form.

The enormous Susanoo dissolved into scattered dark green chakra and returned to the world.

"The ocular power in my eyes has suffered irreversible damage. They still aren't Eternal Mangekyō Sharingan."

"No—that's not quite right. It isn't entirely irreversible. My ocular power recovers so slowly that the rate is practically negligible."

For Uchiha, who revered strength, it was hard to resist the urge to use their ocular techniques after gaining the Mangekyō Sharingan. The real reason they lost their sight was that their eyes didn't get enough rest and time to recover.

"Before I go completely blind, I can still activate Susanoo's Third Form three or four more times. I'll have to use my Mangekyō sparingly from now on."

Before attaining the Eternal Mangekyō Sharingan, every Mangekyō faced the same problem.

[Congratulations, host, on successfully awakening the Mangekyō Sharingan. Please head to Kirigakure as soon as possible to meet Uchiha Madara in person. Reward: Fire Style proficiency +50%.]

"Fire Style proficiency increased by 50%? That'll give my Fire Style chakra another boost. But why does Uchiha Madara want to meet me in Kirigakure?"

Whatever Uchiha Madara was planning, he had lost his Rinnegan and only had transplanted Three-Tomoe Sharingan. Shisui wasn't worried that he could threaten his life.

Shisui was still planning when to set out for Kirigakure and had no idea that an unexpected guest had already arrived at his home.

"Clan Head, what brings you here?"

As soon as Shisui entered the house, he saw Clan Head Fugaku Uchiha waiting in his courtyard.

"You're back, Shisui. Let's talk."

There was nothing unusual in Fugaku Uchiha's tone, but Shisui knew he was most likely here because of the Mangekyō Sharingan.

"Have your eyes evolved again?"