Hinata inhales once. The space behind her brow tightens like a door frame considering a guest.
"Byakugan," she says, barely more than breath.
Her eyes pale until the blue is memory. A fine lace of veins creeps from her temples and settles there like a truth that only arrives when it has to.
Iruka pitches his voice for the room. "Class, observe without pointing. Hinata will describe what she sees. Izayoi will keep his hands visible. No one else moves."
Izayoi lifts his palms to chest height. Honest hands buy cheap quiet. He does not look away from Hinata. He does not look into the pale of her eyes either. Staring turns respect into pressure.
Hinata blinks once with eyes that do not need blinking. "I can see the tenketsu," she says. "They are... quiet."
"Quiet how," Iruka asks, tone a thread pulled gently.
"Like... like water already on the brush," she says, searching for a thing she is allowed to say. "There is no dry drag when he begins."
Iruka nods. "Good image. Now tell me what happens before he moves."
She frowns, then relaxes her forehead by choice. The veins at her temples thicken half a line. "His chakra slides along the skin first. Thin. It avoids catching on edges."
"Edges," Iruka repeats for the class. "The edges of what."
"Elbow," she says softly. "Shoulder. Hip. Ankle. He files them."
Naruto whispers to his own notebook, "Files them," as if the words could sand his next mistake down.
Iruka points at Izayoi's wrists without touching them. "Clone. Slow. Narrated by Hinata. Hands visible."
Hinata steadies. "He decides the after first," she says, and the phrase arrives without apology. "Then he wets the outline. Then he places weight where the after will need it - before the body goes there."
Izayoi lets the clone unfold to his left. Not pop - unfold. The room hears what it does not hear: no breath snatched, no desk legs skated.
"Again," Iruka says. "This time, Hinata, tell me if the chakra pool inside the chest changes before he speaks."
She listens with her eyes. "It does not swell," she says. "It thins and widens. The center stays small."
"Restraint," Iruka says, for notes that need a label. "Substitution. Slow."
Hinata watches the map in front of her. "He puts weight in his feet where the next ground will meet him," she says, almost surprised by her own sentence. "The ankles do not lie. The tenketsu at the skin do almost all the work."
Izayoi trades places with the empty space beside Hinata and returns to where he stood. Hands still visible. Ankles still where the chalk remembers them.
Iruka lets the room breathe. "Questions?" he asks, eyes on the benches rather than the two in the circle.
A hand lifts halfway and lowers. A boy says, "Sensei, can Byakugan see if someone is lying." Hinata flushes and shakes her head once. Iruka says, "Ask me that again when you can notice your own shoulders," and the room smiles without breaking the frame.
Iruka gestures to the windows that cut bright rectangles on the floor. "Light helps you see the edges you forget. Hinata, keep Byakugan active. Izayoi, stand in the window plane. Naruto, stay seated. Everyone else, eyes up, pencils down."
Izayoi steps into the light. Dust floats like small choices looking for a home. Hinata's pupils do not exist anymore - or perhaps they exist as work.
"Describe his outline in the light," Iruka says. "Shoulders, elbows, wrists. Then tell me what changes when he speaks the first seal."
Hinata breathes in for courage and uses it on an answer, not on herself. "His shoulders are quiet. Elbows soft. Wrists honest. On 'Tiger,' nothing moves that the light can notice. The tenketsu near the surface begin to flow."
Iruka's chin tips a degree. "On 'Boar'."
"His ankles get ready," she says. "Not by moving. By choosing where stillness is."
Naruto writes as if the page will run away without ink to hold it.
"Now - moving reference," Iruka says. He nudges the same front row chair a finger to the left, then back. "He will meet the drift. Describe only what you can see."
Hinata watches the soft shift of wood and boy. "He chooses the after before the chair has finished choosing its new place," she says. "He thins along the skin. The center stays small. There is... there is a quiet around him when he moves."
"Quiet," Iruka says, the word a nail set with one careful tap. "What does quiet look like."
"It looks like less," she says, and then blushes at the size of what she has said. "Less change than I expected for the result."
Iruka lets his nod be a thank you. He looks at Izayoi. "Transformation. Minimal. Detail - not show. Then cancel."
Izayoi tips his chin and says, "Ram." He lets the skin over the nose sharpen by a fraction, the scar mirroring exactly. He holds the change for one beat and releases it. Hinata watches the change from the inside.
"The outline shifts at the surface," she says. "The flow moves into the shape he chooses, but it never swells. He keeps the center... small."
"Good," Iruka says. "Now - awareness only. Hinata, eyes remain active. Izayoi, close yours. Hands visible. On my count, you do a slow substitution to the chair behind Naruto. No collision. Call only the first seal. After, you return to the same window line, slow."
Izayoi lifts his palms higher where everyone can see them. He closes his eyes. Before. The classroom waits like a held breath.
"One," Iruka says.
"Tiger," Izayoi answers.
Hinata watches the lines that are not lines. "The surface flows," she says quietly. "The ankles choose the ground that is not there yet."
"Two," Iruka says.
Izayoi trades with the empty air behind Naruto's right shoulder, then breathes back to the light. Naruto chokes on a laugh he did not mean to have.
"Describe his return," Iruka says.
"It un-happens without undoing," Hinata says. The sentence lands and surprises her because it is true. "He is back before I can catch what he did inside the center. The quiet does not break."
"Enough," Iruka says. "Hinata, deactivate. Blink and drink water. Naruto, bring her cup."
Hinata bows a degree, releases her sight, and the blue rushes back into her irises like a tide that knows the shore. The veins at her temples relax. Naruto is already up and already back with the cup - the rare errand he can run without causing a wave.
"Thanks," Hinata says, both hands around the paper cup, as if warmth might hide her hands' small tremor.
Iruka addresses the room. "What we learned. Shoulders tell. Ankles tell. Centers lie if you let them get proud. We will use light this afternoon to teach what lines are supposed to do. No one activates anything without supervision."
He turns back to Hinata. "How long can you hold Byakugan without a headache."
She does not guess. "Ten minutes comfortably. Fifteen if I am careful. Longer if I rest between."
"Good," Iruka says. "We will never push past ten in class. If you feel pressure, you say 'stop.'"
She nods.
Iruka faces Izayoi. "Hands still visible. We'll do a thin pass through the window light again. Hinata will narrate only once - one word per moment. No sentences. The rest of you - write only those words."
Hinata sets the cup down, finds her breath, and raises her eyes again. Byakugan blooms quietly. The room holds its own posture.
"Begin," Iruka says.
Izayoi does not give the room something to chase. He lets movement be a math problem with no extra ink. Hinata gives the single words when they arrive. "Choose. Thin. Place. Edit. Return."
Iruka waits until every pencil has moved at least once. "Now - Naruto and Shikadai, reverse the chairs in row three. Slowly. Make the light different. Hinata stays active."
The two boys obey with the solemnity of people allowed to touch furniture in public. The rectangles on the floor slide like maps reprinted.
"Hinata," Iruka says. "From here - what can you see through the window."
She looks - not far, just out. "The corridor," she says. "The rail. The place where the stairs turn. The dust in the beam."
"Can you see movement three doors down."
"Yes," she says, unsure if saying yes makes her important or merely accurate. "A teacher. Carrying a stack of papers."
"Good. Back to the room."
She returns her focus. The veins hold steady. "Ready," she adds, unbidden, and blushes for adding anything at all.
Iruka claps once. "Final pass for the morning. Izayoi will perform three substitutions between window and chair and window again. Hinata will keep words to one per action. Last pass - no words at all. Class - no pencils. Eyes only. You will tell me later if you actually watched feet and shoulders, or if you played imagination games."
He lifts his hand.
"One."
"Tiger," Izayoi says.
"Choose," Hinata says.
He trades with the window light and back.
"Two."
"Boar," he says.
"Thin," she says.
He brushes the air behind Iruka and returns to the plane of light.
"Three."
"Ox," he says.
"Place," she says, and then lets no more words live where her breath needs the room.
Iruka lowers his hand. "Last pass. No words. Honesty only."
Izayoi keeps his palms high, then lowers them exactly one finger width - still visible, still honest. He sets his breath where the after will be and lets the clone arrive and the substitution happen and the undo be the sort that never shows off. The window accepts him because windows accept light that knows its manners.
Silence holds. Then Iruka speaks and the spell is just class again. "Deactivate."
Hinata releases the sight. The veins soften. She blinks like a person again and rubs the corner of one eye with a careful knuckle.
"How is your head," Iruka asks.
"Fine," she says. "Warm."
"Drink more," he says.
She does.
Iruka turns to the room. "Homework. One: write three sentences that describe a movement without naming a seal. Two: when you walk home, watch your ankles on the last ten steps. Do they lie. If yes, fix them. Three: draw the room's light at noon in your mind and test if you can remember where the rectangles fall."
A hand goes up - the boy who asks about cats. "Sensei, what if it is cloudy at noon."
"Then you memorize how cloudy looks at noon," Iruka says. "If you need sun to learn, you will fail on missions."
Naruto raises a hand without waiting. "Sensei, can I learn the eyes thing later - I mean not the eyes but the noticing part."
"You are learning it now," Iruka says. "You counted out loud and then you learned to be quieter. That is the same muscle."
Naruto grins as if someone just told him he owns a muscle he can train.
Iruka picks up a fresh stick of chalk and draws a short vertical line on the board. "This is your center when you are loud," he says. He draws a thinner line next to it. "This is your center when you are useful." He raps the thin line once. "We aim for useful."
He sets the chalk down. "We will break for water and return. After break - corridor windows, moving reference with crowds. Same rules: no collisions, hands visible, words first."
He almost dismisses them. He does not. He looks at Hinata again, then at Izayoi, then at the door.
Mizuki leans in the jamb with that same tidy politeness, waiting to be noticed rather than taking being noticed for granted. "Iruka," he says, holding nothing this time. "Do you have a moment after break for a quick formality concerning Byakugan use in class."
Iruka says, "Yes," which is what good processes sound like.
Mizuki inclines his head to Hinata. "Thank you for your demonstration. It helps the office write the right rules."
Hinata bows very small. "Yes."
Mizuki steps back so his presence is not a weight. The door breathes.
Iruka looks at the clock that is just a square of light and not a clock. "Ten minutes," he says. "Drink. Do not run. If you run, you pay."
Benches scrape. Paper whispers. Naruto rises like a rocket that learned to lift slowly. Izayoi stays by the window because moving when a room moves makes noise.
Hinata takes two careful sips and then another. She sets the cup down and, to no one in particular, says, "When you moved the last time - the center did not get bigger."
Iruka hears it and stores it. "After break," he says. "We will find out what happens when the world is not this quiet."
He lifts two fingers in the air - the kind of signal rooms obey without anyone telling them why.
"Izayoi," he says. "After the water - window to corridor landing. Hands visible. No seals called. Hinata, eyes active. I will be ten paces behind."
He lets the instruction hang like a doorway built out of words.
"Ready," Iruka says as the room quiets back down from the small chaos of cups.
"Begin."