After that first "chat" with the One-Tails, I started hitting the temple way more often. My curiosity was redlining. Sure, the big sand-raccoon was interesting in a "terrifying disaster-class energy source" kind of way, but what really hooked me was the system Grandpa Bunpuku was using to keep him contained.
This time, I didn't bother asking about Shukaku right away. Instead, I put my engineer's eyes to work on the temple itself. When I'd first arrived, I thought it was just a dump. But now that I knew it was holding a Tailed Beast, my brain started scanning for the "how."
I noticed that the cracks in the stone walls weren't just random weathering. If you looked at them from the right angle, they formed incredibly complex, repeating patterns. The way the floor tiles were laid out wasn't just "shabby chic" either; it was a geometrical grid. Even the way the oil lamp flickered seemed to follow a specific frequency.
The whole building wasn't just a temple. It was a giant piece of hardware.
"Hey, Grandpa..." I pointed to a faint, swirling carving on the wall that looked like a stylized whirlpool. "What's the deal with these marks? They look way too symmetrical to be accidental."
Bunpuku opened his eyes, and I saw that flash of surprise again. Most people probably walked past these marks for decades without seeing anything but old stone. My high-def observation skills were basically a cheat code.
"Those," Bunpuku said, his voice warm, "are what we call Sealing Formulas."
"Fuinjutsu?" I repeated the term. It sounded like... energy programming.
"Exactly," Bunpuku nodded. "Everything in this world has an energy flow Chakra. Sealing is the art of guiding, restraining, or even cutting off that flow entirely. It ranges from putting a few tools into a scroll to something as... big... as this." He didn't finish the sentence, but he glanced at his own shackled wrists.
"So it's like a circuit breaker for his energy?" I asked, my inner engineer geeking out.
"In a way, yeah. You're quick on the uptake, Sayo. The core is the 'Formula' the patterns you see. Some are cages, meant to lock things down. Some are binders, used to hold things in place. Others are like dams, meant to channel and control the flow so it doesn't overflow."
He held up a finger and drew a symbol in the air. A faint, glowing blue trail followed his fingertip. It was a simple design a few circles and straight lines but I could feel a weird, subtle pressure coming off it.
"This is the most basic Seal," Bunpuku explained. "It's the foundation for everything else."
I stared at it, not blinking. My brain went into full "save as" mode, recording every stroke, every angle, and the exact feel of the Chakra. I was already doing a structural analysis in my head. Are those curves meant to distribute the energy load? Are the right angles there to create a focal point?
"God, that's pathetic! The efficiency on that is trash, old man!"
The voice rumbled out of Bunpuku's chest Shukaku was awake and apparently had thoughts. "You've got at least a 5% energy leak at that junction! It's like trying to hold back a flood with a screen door. That turn needs more pressure, or it's just a broken basket!"
Bunpuku just gave me a helpless, "kids these days" smile. "Well, as you can hear, Shukaku has his own... unique perspective on the subject."
"Perspective? I've been the one getting poked by these things for seventy years!" Shukaku barked. "I know where the weak spots are better than any of you humans!"
I leaned forward, looking at the spot in the air where the chakra was fading. "Okay, then how do you stop the leak, Shukaku?"
I asked it like I was consulting a grumpy senior tech on the factory floor. No fear, no judgment just a "help me fix this" attitude.
"...Huh?" Shukaku sounded caught off guard. He huffed for a second, then went back to his arrogant shouting. "Obviously, you gotta pump more juice into the core nodes! It's like plugging a hole in a pipe. And that closing circuit? It's too soft! It's wishy-washy! You need to be crisp with it! Understand? CRISP!"
It was crude, and he was being a jerk about it, but the logic was solid. Bunpuku was giving me the theoretical framework the textbook definition while Shukaku was providing the real-world "user experience" feedback. It was the perfect learning environment.
Bunpuku took Shukaku's "advice" and redrew the symbol, tweaking the chakra output at the points the monster had complained about. This time, the glow was brighter, more solid, and the "pressure" I felt from it was twice as strong.
"Whoa," I breathed. "I get it now."
And just like that, the weirdest classroom in the world was open for business.
The teacher: A high-level monk who knew the math inside and out. The TA: A giant sand demon who knew exactly how to break the system. The student: A four-year-old with a thirty-year-old engineering degree who viewed magic as a new programming language.
Bunpuku started teaching me the basic runes, explaining what they did and how they combined. I soaked it up like a sponge, mapping everything to my knowledge of circuits and mechanical stress. Shukaku would chime in every few minutes to mock Bunpuku's "boring" methods or brag about how he'd almost broken out of a specific seal once (which, ironically, taught me exactly where the fail-points were).
Under that dim oil lamp, the ancient art of Sealing was coming alive. I wasn't just learning "magic." I was learning how to code the reality of this world.
Bunpuku watched me, his eyes full of a strange kind of hope. He could see my brain working, see the way I was cross-referencing everything.
The door to the world of energy was finally opening. And behind that door? A lot of very cool, very dangerous possibilities.