The chamber beneath the Hokage Tower was older than the village itself.
Seiji felt the weight of that age as he descended the spiral staircase, his footsteps echoing on stone worn smooth by generations of shinobi who had walked this same path. Torches flickered in iron brackets, casting dancing shadows on walls carved with the faces of Konoha's founders — Hashirama's stern wisdom, Tobirama's calculating gaze, Mito's serene strength, and others whose names had been lost to time.
Sakumo Hatake walked beside him, his white hair catching the torchlight, his gray eyes fixed ahead. The White Fang wore his formal uniform tonight — the standard jonin vest over dark ANBU fatigues, his legendary blade sheathed at his back. His wolf mask hung from his belt, facing outward as if watching for threats.
"You're nervous," Sakumo said quietly.
"No."
"Your chakra is fluctuating. Your heart rate is elevated. Your hands have been clenching and unclenching since we left the surface." Sakumo glanced at him. "I've been doing this for twenty years, Seiji. I know nervous."
Seiji forced his hands to still. "I've faced Hanzo. I've killed jonin. Why would a ceremony make me nervous?"
"Because this ceremony changes everything." Sakumo's voice was gentle. "Once you put on that mask, you're not just Seiji anymore. You're ANBU. You'll see things that can't be unseen. Do things that can't be undone. And you'll have to carry them alone, because no one outside the division can ever know."
"I already carry things."
"I know. But this is different." Sakumo stopped at the base of the stairs, where a heavy iron door barred their path. Two ANBU guards flanked it, their porcelain masks depicting a hawk and a serpent. "In the regular forces, you have comrades who share your missions. In ANBU, you operate alone more often than not. The shadows isolate you. The secrecy isolates you. And the things you do in the darkness... they isolate you most of all."
"Then why do you stay?"
Sakumo was quiet for a moment. "Because someone has to. Because the village needs people willing to walk in the shadows so others can live in the light." He met Seiji's eyes. "The question is: are you willing?"
Seiji thought of Nawaki's unwavering faith. Kushina's fierce warmth. Minato's calm strength. Tsunade's gruff love. Mikoto's gentle hands and soft promises.
They deserve the light. If I have to walk in darkness to protect that, I will.
"I'm willing," he said.
Sakumo nodded and pushed open the iron door.
---
The induction chamber was circular, perhaps thirty feet across, with a domed ceiling lost in shadow. Torches lined the walls at precise intervals, their flames burning with an unnatural steadiness — chakra-enhanced, Seiji realized. At the chamber's center stood a raised stone dais, and on that dais waited Hiruzen Sarutobi.
The Third Hokage wore his formal robes, the red and white hat of his office casting his face in shadow. Behind him stood the three elders — Homura Mitokado, his face unreadable behind round glasses; Koharu Utatane, her expression cool and assessing; and Danzo Shimura, his bandaged face half-hidden, his single visible eye fixed on Seiji with an intensity that felt like a physical weight.
Other ANBU captains lined the walls, their masks a gallery of predators and spirits. Wolf. Tiger. Bear. Owl. Each one a legend in their own right, their identities known only to the Hokage and each other.
Seiji walked to the center of the chamber and knelt before the dais.
"Hyuga Seiji." Hiruzen's voice echoed in the circular space. "You have served Konoha with distinction through the years of the Second Shinobi World War. Your combat record includes the elimination of forty-seven enemy shinobi, the capture of Kitsuchi, son of the Tsuchikage, and direct engagement with Hanzo the Salamander. Your tactical abilities have been noted. Your bloodline — the Tenseigan — has been documented as a unique asset to the village."
The words felt strange, hearing his life reduced to a list of accomplishments and assets. But this was ANBU. This was how they saw people — as tools to be evaluated, weapons to be deployed.
"Today, you are offered a place in the Ansatsu Senjutsu Tokushu Butai — the Special Assassination and Tactical Squad. ANBU. This is not an honor. It is a burden. You will serve in the shadows, without recognition or glory. Your missions will be classified. Your sacrifices will be unknown. And if you fall, your name will not be spoken."
Hiruzen paused, letting the weight of his words settle.
"Do you accept this burden?"
Seiji raised his head. "I accept."
"Then speak your name. Not the name you were given at birth. Not the name the world knows you by. The name you will carry in the darkness. The name that will be whispered by enemies who never see your face."
Seiji had thought about this moment for weeks. A code name was more than a mask — it was an identity. A declaration of who you chose to be when no one was watching.
He thought of the golden threads he saw through his Tenseigan. The life force that pulsed through every living thing, from the mightiest Kage to the smallest insect. He thought of the way those threads flickered and faded when he took a life, and the way they brightened when he saved one.
He thought of his mother's letter. Be brave. Be kind. Be yourself.
He thought of Sakumo's words. Love is the only thing that makes the shadows bearable.
"Yoru no Osu," he said. "The Night's Mercy."
A ripple ran through the chamber. ANBU code names were typically fierce — predators, elements, weapons. Wolf. Hawk. Storm. Blade. Mercy was not a word often spoken in these shadows.
Danzo's eye narrowed. "Mercy is a luxury in ANBU. The shadows do not permit it."
"Mercy is not a luxury," Seiji replied, his voice steady. "It is a choice. One I intend to make, even in the darkness. Especially in the darkness."
The tension in the room sharpened. The other ANBU captains watched in silence, their masks revealing nothing. Sakumo's hand rested briefly on his shoulder — a silent gesture of support.
Hiruzen raised his hand, cutting through the moment. "The name is accepted. Yoru no Osu. Night's Mercy. May you bring swift justice to Konoha's enemies, and may your mercy be reserved for those who deserve it."
He stepped down from the dais and approached Seiji. In his hands was a porcelain mask — white, featureless except for two eye slits. A blank canvas, waiting to be filled with the deeds Seiji would perform in the darkness.
"Wear this mask when you walk in the shadows," Hiruzen said. "Behind it, you are not Seiji. You are not Kotsuhaku. You are Yoru no Osu. ANBU. The village's hidden blade."
Seiji took the mask. It was lighter than he expected, smooth and cool against his fingers. He raised it to his face, feeling the porcelain settle against his skin.
The world changed.
Not literally — his Tenseigan still saw the golden threads of everyone in the chamber, the torchlight still flickered, the stone walls still surrounded him. But something shifted inside him. A distance. A separation. He was still Seiji, but he was also something else now. Someone else.
Yoru no Osu. Night's Mercy.
"Rise," Hiruzen said. "Rise as ANBU."
Seiji rose.
---
The ceremony concluded, but the night was far from over.
Sakumo led him through a series of corridors to a small chamber deep within the ANBU complex. It was sparsely furnished — a table, two chairs, a scroll rack, and a single lantern. The walls were bare stone, unadorned.
"Your first briefing," Sakumo said, gesturing for Seiji to sit. "Every ANBU operative gets one. I'm giving you yours because you're assigned to my command structure."
Seiji sat, keeping his mask on. He wasn't ready to remove it yet. The anonymity felt like armor.
"ANBU operates in cells," Sakumo began, unrolling a scroll that revealed a complex organizational chart. "Each cell has four to six operatives, led by a captain. Captains report to division commanders. Division commanders report directly to the Hokage. In theory."
"In theory?"
"In practice, there are... complications." Sakumo's expression darkened. "Danzo's Root was once part of ANBU. It was officially disbanded years ago, but it continues to operate in secret. Root operatives answer only to Danzo. They pursue his agenda, not the Hokage's."
"I've encountered them. The False Flag mission."
"Yes. And you'll encounter them again." Sakumo leaned forward. "This is what I need you to understand, Seiji. ANBU is not a unified organization. It's a battlefield. Danzo is constantly trying to expand his influence, to recruit operatives to Root, to shape ANBU's mission to serve his vision of Konoha. The Hokage knows this, but he can't move openly against Danzo without proof. So we fight a shadow war within the shadow war."
"How do I navigate that?"
"By knowing who you can trust." Sakumo ticked names off on his fingers. "Me. The Hokage. A few of the senior captains — Tiger, Bear, Owl. Everyone else... be careful. Danzo's reach is long, and his agents are everywhere."
"What about my code name? Why did Danzo react that way?"
"Because 'Mercy' challenges everything he believes." Sakumo's voice was quiet. "Danzo sees shinobi as tools. Weapons to be used and discarded. He doesn't believe in mercy. He believes in control. By choosing that name, you declared that you're not his kind of weapon. He won't forget that."
"Good. I don't want him to."
Sakumo studied him for a long moment. "You hate him."
"He tried to have me killed. He threatened everyone I love. He's destroying your reputation piece by piece." Seiji's voice was flat. "Yes. I hate him."
"Hatred is a fire that burns the one who carries it more than the one it's aimed at."
"I know. But I'm not carrying it as fire. I'm carrying it as clarity." Seiji met Sakumo's eyes through the mask. "Danzo is a threat to everything I want to protect. Knowing that isn't hatred. It's awareness."
Sakumo was quiet. Then, slowly, he nodded.
"You're wiser than I was at your age." He rose. "Get some rest. Tomorrow, you receive your first assignment."
"What is it?"
"A black market intelligence network in the Land of Rivers. They're selling Konoha's border defense plans to the highest bidder. Your job is to infiltrate, eliminate the leadership, and recover or destroy the intelligence."
"Targets?"
"Seven confirmed. Possibly more. The leader is a former Kumo jonin named Raiun. Lightning-style specialist. Dangerous."
Seiji nodded. "I'll be ready."
"I know you will." Sakumo paused at the door. "One more thing. The mask — it becomes a part of you. Don't let it consume who you are. Remember that behind it, you're still Seiji. Still the boy who saved his friend. Still the boy who loves a girl in Konoha. Hold onto that."
"I will."
Sakumo left, and Seiji sat alone in the small chamber, the lantern flickering, his white mask reflecting the light.
Yoru no Osu. Night's Mercy.
He removed the mask slowly, feeling the cool air on his face. His reflection stared back at him from the porcelain surface — silver-white hair, pale eyes with their faint crimson ring.
He was still Seiji.
But he was also something more now.