Opening the notebook to the very first page, Genma's eyes were greeted with densely packed lines of text.
Shiranui Yukima's handwriting was not elegant, but it was neat and forceful, almost as if the words were carved into the paper.
The opening pages recorded Yukima's experiences when he first entered the academy, along with scattered personal reflections—more like casual essays. Genma skimmed through them and quickly flipped ahead to the section on the Three Basic Jutsu.
The Three Basic Jutsu referred to Transformation, Clone, and Substitution—three essential jutsu every shinobi had to master. To possess these three was to gain, at the very least, a sliver of hope to survive on the battlefield.
At the genin level, both the Transformation and Clone Jutsu were shallow forms of genjutsu—visible but without substance, and easy to see through.
Of course, in the ever-changing flow of real combat, if used skillfully, even basic Transformation and Clone Jutsu could still turn the tide at a critical moment.
Substitution was a little more complex. According to the notes, its essence was a special type of summoning jutsu. By summoning at short range, the ninja could switch positions with a preselected object, achieving a hair's-breadth escape from danger. (Note)
In his previous life, Genma had always thought of the Substitution Jutsu as a kind of bug. But now, he realized its limitations were far from few.
Even choosing the substitution object was a hassle. The beginner's version could only target solid, dense objects like logs or rocks, and only if they were close by. Against a skilled opponent who simply cleared the area with a large-scale jutsu, the Substitution Jutsu became all but useless.
Not only that—activating the jutsu also required the ninja to first perceive the danger. And in battle, full of traps and ambushes, no one could guarantee they would always detect the threat in time.
In short, the Three Basic Jutsu were all jutsu that relied heavily on application. Learning them was not difficult—using them well was the real challenge.
Genma frowned thoughtfully for a moment, then flipped through a few more pages, hoping to find some practical offensive techniques, something like the Rasengan—a jutsu that required no hand seals.
He leafed through the notebook for a while. Indeed, there were plenty of offensive techniques recorded—wind release, fire release, even some kenjutsu. But something like the Rasengan… there was nothing.
A bit disappointing, though not unexpected.
After all, not everyone had a background as privileged as Naruto. Besides, at this point in time, Namikaze Minato probably hadn't even developed the Rasengan yet. Even if Genma wanted to learn it, there was nowhere he could.
Shaking his head, Genma flipped a few more pages—then froze.
"…Huh?"
On this page, the handwriting suddenly turned messy and uneven, completely different from the neat, powerful strokes from before.
He realized at once—this must have been written after his father lost his right arm. Everything from here on had been written with his left hand.
The content also shifted abruptly. Where before it had been ninjutsu and kenjutsu, this page was suddenly a detailed discussion of Yukima's understanding of hand seals.
It read:
"...Chakra is composed of both spiritual and physical energy. Naturally, then, the strings that control chakra are twofold—one from the spirit, one from the body."
"Though every part of the body can influence chakra to some degree, the hands are without doubt the body's most flexible tools. They change endlessly, and are blessed with keen sensitivity. Thus, the chakra string that stems from the body is closely entwined around the ninja's ten fingers. But this does not mean that one who loses their hands is forever barred from becoming a shinobi. At the very least, one who has lost a single hand can still weave seals. From what I've heard, there are even some geniuses capable of forming seals with only one hand…"
One-Handed Hand Seals…
Genma recalled that indeed, there were shinobi capable of forming seals with just one hand—for example, Haku and Namikaze Minato.
Aside from that, there were also unusual methods like Jiraiya's use of his feet to form seals. Some were even rumored to cast jutsu without seals at all—Uchiha Itachi seemed to be one of them, though the original story never made this explicit.
But whether it was one-handed seals, foot seals, or no seals at all, such feats were far beyond the reach of ordinary shinobi. At the very least, one had to be a prodigy like Haku. The vast majority of shinobi could only form seals properly with both hands.
Thus, losing an arm was nearly a death sentence for a ninja's career—especially if it was the right arm.
It seemed his old man had longed to master one-handed seals after losing his right arm, hoping to continue his life as a shinobi. Only… why was there no follow-up?
Flipping a few pages ahead, Genma saw the notes on hand seals abruptly end, giving way once more to the earlier style—records of ninjutsu, observations, and, curiously, daily trivia never seen before. Likely, after losing his arm, Shiranui Kōma had more idle time at home.
Indeed, Genma's own memories of his father were almost entirely of him living quietly after the injury.
It wasn't until the outbreak of the Second Shinobi World War that Kōma once again took up missions, serving as a Konoha chūnin.
So in the end, had his attempt at one-handed seals succeeded?
The significance of one-handed seals was obvious. If a ninja could master them, they would have one hand free while casting a jutsu—a hand that, in a fight between equals, might well decide the outcome.
At that thought, Genma immediately began flipping quickly through the notebook.
Page after page, he saw the messy scrawl gradually return to neat, powerful strokes—almost indistinguishable from the handwriting at the beginning.
At the same time, records of one-handed seal training began to appear in abundance. Clearly, Kōma had thrown himself into this pursuit with determination.
But… even after reaching the final page, Genma still found no actual method for one-handed seals.
His father had failed.
One-handed seals were, after all, not something an ordinary person could master.
Still, Genma had not come away empty-handed. At the very least, through his father's notes, he now understood the many difficulties and problems one would face while practicing. If he were to attempt to master one-handed seals himself, these records could save him a great deal of time and effort.
Moreover, though Kōma had failed at one-handed seals, he had truly succeeded in one-handed kenjutsu. Near the notebook's end was a detailed account of his process—experimenting, training, and finally forging a style he named the "Left-Handed Blade." (Note)
Without that Left-Handed Blade, a one-armed Kōma likely would never have returned to the frontlines.
After skimming through the Left-Handed Blade section, Genma fell silent for a long time. Then, wordlessly, he flipped through the notebook again, all the way to the final page.
The last entry was his father's final mission, sometime in the mid-to-late stages of the Second Shinobi World War:
"…According to our spies, the enemy tonight will include two powerful puppet masters. I can only hope the antidotes I've prepared won't need to be used…"
Notes:
Since the original explanation of the Substitution Jutsu in the manga (Chapter 6) was somewhat forced, this story uses a modified version.
In Japanese, the word "ken" (sword) is broad in meaning—katanas are considered a type of sword, so the terms can be used interchangeably.