Shinji had previously tested Ido's abilities. When Ido detached from Yakumo's body as a spirit, she could operate within a range of about twenty-five kilometers from Yakumo.
Any farther, and Ido couldn't maintain her spirit form.
But after Yakumo received the Koryugan and survived the First Hokage cell transplant surgery, Ido's power grew alongside hers, receiving a massive boost.
The most noticeable improvement was in Ido's spirit form, which had become significantly stronger.
Now, with Yakumo's permission, Ido could move within a range of about fifty kilometers from her.
Fifty kilometers!
That distance exceeded the detection range of nearly all sensory ninjutsu and dojutsu. Even Karin's overpowered "Mind's Eye of the Kagura" was useless at such a span.
So the current Yakumo effectively had the ability to launch a surprise attack with the "Spirit Transformation Technique" within fifty kilometers—without her body suffering the vulnerability Kato Dan faced when his spirit strayed too far.
At this point, the Yakumo-Ido duo was already terrifying.
But that wasn't their limit.
The Koryugan's fearsome blood manipulation ability had once led Shinji, by a twist of fate, to develop a secret technique called "Blood Clone Jutsu."
This technique required the Koryugan to perform. Having lost the Koryugan, Shinji could no longer use it, so he'd taught its secrets to Yakumo.
Unexpectedly, this opened a new door for Yakumo, who discovered another use for "Blood Clone Jutsu."
When Yakumo cast the technique, Ido could inhabit the blood clone in spirit form, greatly enhancing its capabilities.
A physical blood clone was already stronger than a shadow clone made purely of chakra. But once Ido's spirit entered it, its power skyrocketed—nearly matching Yakumo's real body.
Realizing the potential in this, Shinji had arranged today's test.
"We're about forty-five kilometers from Hidden Leaf—near the edge of your range!" Pausing, Shinji continued: "Today, we're testing whether having a blood clone as a temporary vessel can extend your range even further."
Ido grinned confidently: "Lord, after using 'Blood Clone Jutsu,' that weak, spirit-form feeling is completely gone. In this state, I feel like I could run to another country without any trouble!"
Shinji pointed in a direction: "We'll only know after testing. Go!"
Not daring to defy her leader, Ido shot off with a whoosh, racing like an arrow in the direction Shinji indicated.
"Hmm?"
Shinji let out a soft sound, his brow furrowing slightly.
Ido's speed clearly surpassed Yakumo's.
Theoretically, a blood clone's limit should only approach the original's power—never exceed it.
But Shinji quickly pieced it together.
It wasn't that the blood clone's power outstripped Yakumo's—it was Ido's superior mastery of that power, creating the bizarre situation where the clone seemed stronger than the original.
After a brief moment of surprise, Shinji followed her.
Both Ido and Shinji moved at jonin-level speeds. Since this was a test, they spared no chakra, pushing full throttle. Their speed was so great that the scenery on either side blurred and warped, like a stretched painting.
Soon, they passed the fifty-kilometer limit.
What had once been an insurmountable barrier for Ido now seemed meaningless. She showed no sign of stopping, charging ahead relentlessly.
Sixty kilometers.
Seventy kilometers.
Eighty kilometers.
Even at eighty kilometers from Hidden Leaf, Ido showed no irregularities and kept going, leaving Shinji trailing behind in quiet amazement.
Ninety kilometers.
One hundred kilometers…
Shinji's gaze sharpened.
This was the range limit of his "Jikibi." If he went any farther from the village, he'd lose the ability to connect to Yakumo via "Jikibi."
So he monitored the "Jikibi" link, testing another hypothesis he'd been mulling over.
Before long, Ido, still speeding ahead, crossed the hundred-kilometer mark from Hidden Leaf.
One hundred kilometers was "Jikibi's" limit—beyond that, it couldn't sense or connect to a marked target.
After confirming Yakumo was out of "Jikibi's" range, Shinji activated it, attempting to link to her.
In an instant…
Instead of reaching toward Hidden Leaf, "Jikibi's" sensing locked onto Ido ahead of him. Then something strange happened—Shinji successfully connected to Yakumo through "Jikibi," despite being over a hundred kilometers away from her.
"So it's like that…"
An unexpected outcome, yet Shinji wasn't overly surprised.
He'd run this test because he'd noticed that as Yakumo adapted to the Koryugan, the subtle bond between her and Ido had strengthened significantly.
In other words, as long as either Yakumo or Ido was within his "Jikibi" range, he could use their connection to link to both of them simultaneously.
Confirming this, Shinji mused inwardly: "Though Yakumo and Ido always had this bond, it was never this strong! What amplified it—Koryugan? Or the First's cells?"
Compared to before, Shinji leaned toward the Koryugan.
In the original timeline, the First's cells hadn't shown any peculiar abilities tied to souls or sensing.
But as a dojutsu born from Yin Release chakra, the realms of soul and perception were clearly the Koryugan's domain.
"Could it be a special ability of the Koryugan!?"
A theory sprouted in Shinji's mind.
Meanwhile, Ido ahead of him was like a wild horse off its leash, still barreling forward.
Silently calculating, Shinji realized she was now roughly a hundred thirty kilometers from Hidden Leaf. He called out: "Stop!"
Ido halted at his command.
Shinji looked her over, assessing her condition while asking: "How do you feel now?"
"Fantastic!" Ido smiled: "That constant pull from Yakumo is completely gone. I feel free—like I'm unbound by distance now!"
Shinji thought to himself: "So with a physical body protecting her, Ido's spirit is no longer constrained by distance and can freely stray from Yakumo…"