"Hm? Kushina-senpai wants to see me? Is it about the sword?"
Mikami Yuu paused slightly. "Did she only call for me?"
"According to Jōnin Kushina's instructions, if Nohara Rin or Hatake Kakashi are around, they can come too, but it isn't required," the Anbu replied.
"…Then let's bring Rin."
With Minato not around, it was better to avoid anything that might look improper.
There was no need to call Kakashi or Obito. Yuu didn't know whether Kushina had ever taught them sealing arts in the original story, but it was still best not to let Obito have too much contact with Kushina. Who knew whether the method he later used to break the Nine-Tails' seal had originally come from her—
Twenty minutes later,
Mikami Yuu and Rin arrived at a quiet training ground on Konoha's western side. Uzumaki Kushina was already waiting there. Her bright red ponytail shone brilliantly in the sunlight, and in her hand she was idly twirling a familiar short sword.
A shadow or two could be vaguely seen hidden among the dense bushes in the distance. Presumably they were Anbu assigned to watch over the Nine-Tails' jinchūriki.
"Yo, you finally made it! Rin's here too!"
Kushina leaped down from the wooden post with a delighted grin, hugged Rin, and rubbed cheeks with her before finally straightening up and tossing the short sword to Yuu.
"Here, Yuu. Your sword's been modified already."
Mikami Yuu caught it steadily. It felt a little heavier in hand, and the hilt felt smooth and warm. At a glance, though, it didn't look much different from before.
But when he followed Kushina's instructions and channeled chakra into the hilt, thin black-red lines appeared across the blade, like a porcelain surface covered in fine cracks.
Looking closer, those lines seemed to be made of countless nested triangular structures linked together, forming chakra-ring patterns that connected end to end while rotating out of sync. It carried an aura that was both exquisitely precise and faintly dangerous, with a strange kind of beauty to it.
"This is a Double Binding Formula."
Kushina planted her hands on her hips and explained proudly, "The short sword itself has chakra-conducting metal mixed into it, so it was really convenient to modify. Even if you don't know sealing arts yourself, as long as you pour chakra into the hilt, the formula I carved into it will activate.
"If an enemy gets cut by this sword, their chakra flow will become sluggish for a short time. Ninjutsu, genjutsu—none of it will come out smoothly!"
"Of course, if you want to bring out the full power of that seal, you'll still need to study sealing arts seriously.
"If you're only activating it with raw chakra input, the effect gets discounted. At most, it'll disrupt the enemy's chakra flow and make them a beat slower. It won't easily lock someone down outright."
"Understood."
Mikami Yuu nodded.
So in other words, in its current form, this sword was basically a foolproof sealing tool. As long as it got chakra, it would activate. But any hidden functions beyond that would only reveal themselves once he understood sealing arts more deeply.
And so—
Kushina's little lesson began again.
This time, the focus was the Binding Formula.
According to her, under normal circumstances, this formula required nine hand seals. It involved guiding chakra and precisely constructing nested triangular array structures to form rotating sealing rings. Even a slight deviation could drastically reduce its effectiveness. The learning difficulty was actually higher than medical ninjutsu.
And this still counted as one of the simpler things in sealing arts. Techniques like the Evil Sealing Method, Self-Cursing Seal, or even the Four Symbols Seal were much more complicated, requiring over a dozen different rune arrays just to memorize.
Rin was starting to look a little overwhelmed, but still did her best to memorize and understand the dense, interwoven lines of symbols.
Mikami Yuu was equally focused, trying hard to keep up with Kushina's train of thought.
Then, all of a sudden, a familiar prompt popped up in his vision—
[Ding! High-quality potential romance target detected: "Binding Formula"! Time-limited encounter triggered!]
"It's here!"
Mikami Yuu's spirits lifted instantly.
[You accidentally fall into the depths of an icy prison. Under dim light, you see the figure of a red-haired girl. She's curled up in a corner with her knees hugged to her chest, wearing a long black dress made of complex runic lines. Her long hair covers most of her face, and both her arms and ankles are wrapped in cold chains, leaving red marks on her pale skin. An aura of dark isolation radiates from her, warning others not to come close.]
[Talk]
[A: Hi, I'm Mikami Yuu. Sorry to bother you. Do you need help?]
[B: Wow, those chains are beautiful. Wrap me up too!]
[C: Hey, lift your head. I said lift it. Let me see your face!]
"So… this one looks like a gloomy type?"
Kind of like Water Formation Wall—
After a moment's thought, Yuu cautiously chose A.
[Her body trembles slightly, like a startled caged beast. Then the face buried in her knees slowly lifts, revealing a pair of hollow black eyes like stagnant water.]
[Binding Formula: Help? Heh… another self-righteous fool. I wrapped these chains around myself. The only point was to shut out the noisy world outside. You'd better hide somewhere and stay out of my sight. Don't bother me, or else… heh.]
"Holy…"
Gloomy, withdrawn, and with self-harm tendencies—
This was a full-on landmine girl.
If he actually romanced this one…
Would that cause problems?
What if the formula started activating on its own and sealed him by accident—
"Hey, Yuu? What are you spacing out for? Did you understand that part just now?"
Kushina's voice pulled him back to reality.
"Ah, sorry. I zoned out for a second. Could you say that last part again, Kushina-senpai?"
Mikami Yuu came back to himself and pressed his palms together apologetically.
By all logic, sealing arts and a landmine girl did match pretty well as a type, but romancing a "pretty girl" with this personality was going to be difficult. Yuu decided to test the waters first and take it slowly.
That night, Kushina treated Mikami Yuu and Rin to a meal at Ichiraku Ramen.
Of course, Anbu shadowed them the entire time.
After all, this was Konoha's Nine-Tails jinchūriki. Absolutely nothing could be allowed to go wrong—especially when Minato, that human stabilizer, wasn't in the village.
Yuu took the chance to ask about Minato's situation.
But Kushina didn't seem to know much either. She only said he had gone out on a high-level mission. Still, according to the original story, Minato had at least another three or four years left to live, so there would be plenty of chances to interact with him later. No need to worry about missing the chance to learn Flying Thunder God.
Just as the meal was ending,
Kushina tilted her head as if remembering something, then looked at Mikami Yuu and Rin with obvious curiosity.
"Oh right, Yuu, Rin—I suddenly want to ask you something personal.
"Are you two a couple?"
"…???"