Chapter 65: Barrier Class 

"Eightfold Flavor. Genjutsu. Taught by your sensei." 

Every answer from Iruka made Mizuki's mouth taste worse. 

He knew Tobitake Tonbo. Two years earlier, Mizuki had sparred with Iruka and learned enough about the former team to identify its captain. Training methods copied indirectly from Iruka had helped Mizuki reach chūnin sooner than he would have managed alone. At the time, he wished Tonbo had chosen him instead. 

That wish had become resentment. The old genin team had dissolved, yet Tonbo continued giving Iruka original techniques. Mizuki saw no reason the orphan should receive loyalty from a teacher, approval from Hiruzen, and a position at the Academy while Mizuki remained unnoticed. 

"Your sensei must value you greatly," he said with a broad, false laugh. "Do not worry about me. Your progress is more important." 

Iruka relaxed. "Sensei is impressive, but his humor is terrible. You experienced the technique yourself; it is not intended to kill anyone. He gave it to me as a way to discipline inattentive students." 

The mention of students darkened Mizuki's thoughts. 

Both men had passed the Academy's instructor examination. Iruka's appointment moved forward, while Mizuki's remained delayed because a previous mission raised suspicion that he had allowed a teammate to die for the objective. 

Mizuki considered the judgment hypocrisy. Sakumo Hatake had been condemned for abandoning a mission to save comrades. Mizuki pursued his orders and lost every chance at advancement, although no tribunal proved that he killed anyone. Konoha praised sacrifice and duty only when convenient. 

He omitted the choices that made his case different. Sakumo had accepted responsibility openly; Mizuki's account shifted whenever investigators pressed the sequence of events. The absence of a conviction did not make the surviving reports trustworthy. Resentment allowed him to treat uncertainty as persecution. 

He blamed the Hokage, the village's inconsistent standards, and especially Iruka for receiving the recognition Mizuki believed he had earned. 

His smile revealed none of it. 

At Konoha's restricted ninjutsu archive, Tonbo studied a scroll placed alone on a table. 

The listed creator surprised him. "The First Hokage developed Bringer-of-Darkness?" 

Tonbo had assumed Tobirama created the technique because of its value against the Sharingan. Hashirama's authorship made equal sense when considered historically. Before Konoha, the Senju and Uchiha spent generations at war. Both clans developed methods specifically to counter the other's inherited advantages, and Hashirama possessed talent far beyond Wood Release alone. 

"You have one hour," an ANBU guard said. A full unit watched the chamber from fixed positions. "Memorize the formula here. The scroll does not leave this room. If time expires, you must request access again." 

Tonbo had already passed several reviews to enter. Bringer-of-Darkness was a restricted technique and one of Konoha's military secrets. 

He extended his senses across the scroll. Seals, chakra pathways, timing, and warnings entered his memory as a structured whole. A barrier around the chamber prevented perception from reaching beyond its walls, but everything inside remained clear. 

The ANBU watched his hands as carefully as his face. Tonbo could study, trace seals in the air without chakra, and ask questions, but any attempt to copy the scroll physically would end the session. Even his sensory method remained confined to the chamber so that no hidden partner could receive the formula from outside. 

Fifteen minutes later, Tonbo understood enough to reproduce the complete formula. Finishing immediately might invite inconvenient questions, so he continued studying the relationships between its parts. 

Bringer-of-Darkness was an A-rank, close-to-mid-range auxiliary genjutsu. It deprived targets of sight and replaced every source of light with absolute darkness. The complexity lay not in presenting a black image, but in overcoming the victim's visual chakra pathways strongly enough that even a Sharingan could not restore reliable perception. 

The formula attacked the assumption that sight remained available. Instead of drawing a false object over the world, it interrupted the target's ability to assign meaning to incoming light. A dōjutsu could continue receiving detail and still report nothing useful to the conscious mind. 

Improper use carried a severe danger. A caster who misdirected the technique could trap his own visual system and lose access to light without knowing how to release it. 

Tonbo found the risk acceptable and the theory invaluable. 

His first confrontation with Shisui succeeded partly because the Uchiha lacked information. A second fight would begin with Shisui prepared for genjutsu, watching chakra flow and using mobility to avoid obvious delivery paths. Tonbo's defensive techniques could obscure some information about his own body, but they could not make every thread of released chakra invisible. 

Most genjutsu entered a target's chakra system and disrupted the information reaching the mind. Recognize the intrusion, interrupt the flow, and the illusion broke. Exceptional techniques such as Kotoamatsukami, Izanami, and the Living Weave operated through different rules. 

Bringer-of-Darkness offered another model. By understanding how it defeated enhanced visual perception, Tonbo could improve his subtler illusions against dōjutsu instead of relying on surprise. 

He left the archive satisfied. 

Later, at a restricted Barrier Team training ground, three shinobi waited for him. 

"Only three?" Tonbo asked. 

The leader wore a flak jacket and possessed the pale eyes of the Hyūga clan. "We maintain and monitor Konoha's barrier systems. Hokage-sama ordered us to join your development unit and learn from you." 

Tonbo had expected more personnel until he considered the secrecy of the project. A small core could experiment without exposing Sealed Horizon's structure across the entire Barrier Team. Once the design became stable, additional shinobi could be trained for construction and maintenance. 

The other two appeared unremarkable, which revealed nothing about their expertise. 

"A Hyūga working with the Barrier Team," Tonbo said. 

"Hyūga Tetsugan," the man introduced himself. 

Members of the major clans served throughout Konoha, and a Byakugan offered obvious value in sensing and inspecting chakra structures. Tonbo set aside his surprise. 

"Hokage-sama explained the objective?" 

"We are to develop a defensive barrier capable of resisting attacks across an enormous area." 

Neither Tetsugan nor his partners challenged Tonbo's authority. Barrier maintenance protected the entire village, and Hiruzen would not place an outsider over the project without reason. 

Tonbo looked across the empty field and considered the scale between Sealed Horizon Barrier and Konoha itself. 

The original technique protected one training ground by confusing perception and sealing its boundary. A village system needed distributed anchors, redundant chakra supplies, access rules for thousands of residents, and a response when one section failed. Expanding the radius without redesigning those functions would create a larger weakness rather than a stronger defense. 

Tetsugan activated his Byakugan. The other two unrolled blank diagrams and prepared measuring tools. Tonbo placed the first anchor at the center of the field, giving them a concrete structure around which to test every assumption. 

Work began immediately. 

"Then we begin with the first stage of the large defensive system: Sealed Horizon."