Arc 1Thunder and Vengeance

After a demon killed his parents, Uesugi Sasuke used the Sasuke Template System to hunt demons and gain powerful techniques. He trained under Jigoro Kuwajima, awakened the Sharingan, and mastered a controlled Chidori, but Kuwajima challenged him to find something worth protecting as Sasuke continued training alongside Zenitsu Agatsuma.

  • Uesugi Sasuke found a gray-skinned demon devouring his father, and after it nearly killed him, his hatred awakened the Sasuke Template System and healed his injuries.
  • Uesugi Sasuke escaped the demon, buried his parents, and swore revenge before the system sent him to hunt three lone demons for revenge points.
  • Uesugi Sasuke killed demons to unlock the Great Fireball Technique and Chidori, then injured himself when Chidori’s speed carried him toward a cliff.
  • Uesugi Sasuke traveled to Mount Momoyama and persuaded Jigoro Kuwajima to teach him Thunder Breathing after demonstrating his dangerous lightning power.
  • Uesugi Sasuke struggled with swordsmanship and Thunder Breathing while training alongside Zenitsu Agatsuma, then combined breathing with chakra to awaken the One-Tomoe Sharingan.
  • Uesugi Sasuke used his Sharingan to learn Thunder Breathing’s opening stance and control Chidori, piercing a boulder without losing control.
  • Jigoro Kuwajima challenged Uesugi Sasuke to find something to protect and ordered him to swing his sword a thousand times each day.
  • Uesugi Sasuke sparred with Zenitsu Agatsuma, who suddenly used Thunderclap and Flash before collapsing unconscious, leaving Sasuke wondering about his hidden power.
Chapters 1–25 Vol. 1 Read

Ch. 1A boy named Uesugi, and the last moment of peace

Twelve-year-old Uesugi Sasuke returned home from gathering firewood and shared a peaceful dinner with his parents, despite warnings about dangerous beasts in the mountains. In the night, a monster attacked his family, and Sasuke found his parents dead as it turned toward him.

  • Uesugi Sasuke carried firewood home and joined his parents for dinner.
  • His mother warned him about fierce beasts attacking livestock, and his father told him to be careful in the mountains.
  • After falling asleep, Sasuke woke to strange noises and heard a growl from his parents' room.
  • Sasuke grabbed his woodcutting blade and broke into the room.
  • He found his father mutilated and his mother dead while a gray-skinned monster devoured his father's body.
  • The monster turned toward Sasuke with a bloodthirsty smile.

Ch. 2The night of the massacre, a scarlet light amid despair

Uesugi Sasuke was cornered by the monster that had killed his father and seemed certain to die. His desperate hatred activated the Sasuke Template System, which healed him and armed him with new knowledge and a kunai as the monster paused in confusion.

  • Uesugi Sasuke tried to strike the monster with a billhook, but it knocked the weapon away and slammed him into a wall, breaking his ribs.
  • Sasuke lay helpless as the monster approached, then vowed in his thoughts that he wanted to kill it and avenge his family.
  • Sasuke's intense hatred triggered the Sasuke Template System, which began integrating a template into him.
  • Sasuke received knowledge of chakra, ninjutsu, taijutsu, genjutsu, Sharingan, and Chidori as energy flowed through his body and rapidly healed his injuries.
  • Sasuke's clothes transformed into training clothes, and a kunai appeared in his hand; he opened his eyes with calm resolve and burning hatred while the monster watched in confusion.

Ch. 3A beginner's gift pack? Fighting with a Kunai!

Uesugi Sasuke used his newly enhanced reflexes and a burning oil lamp to escape the man-eating demon. He fled into the dark forest, leaving the demon trapped inside the house by the flames.

  • Uesugi Sasuke dodged the man-eating demon’s claws and discovered his body had become slightly faster and stronger.
  • Sasuke stabbed the demon’s shoulder with a Kunai, but it regenerated and attacked him again.
  • Sasuke realized demons feared sunlight and used the oil lamp near the kitchen to set a barrier of fire between them.
  • Sasuke threw burning firewood at the demon, escaped through a kitchen window, and ran toward the forest.

Ch. 4An oath upon the ruins

Uesugi Sasuke survived the night after a demon attacked his home and found his parents dead in the burned ruins. He buried them and swore to kill every demon, leaving his life bound to revenge.

  • Uesugi Sasuke emerged from a tree hollow at dawn and made his way back to his home.
  • Uesugi Sasuke found his house burned down and discovered his parents’ charred bodies in the ruins.
  • Uesugi Sasuke dug two graves and carefully buried his parents’ remains.
  • Uesugi Sasuke kowtowed before the graves and swore to avenge his parents by killing every demon.

Ch. 5The Starting Point of Revenge

Uesugi Sasuke’s revenge vow activated a system that offered power for slaying demons. After receiving a quest to kill three lone demons, he left his parents’ graves and headed into the forest toward his first target.

  • The system activated its main quest after Sasuke solidified his resolve for revenge and displayed his abilities, revenge points, and unlockable skills.
  • Sasuke learned that killing demons earned revenge points and that he could use them to unlock powerful techniques.
  • The system issued an introductory quest to slay three lone demons and marked the nearest demon’s location in the forest east of the village.
  • Sasuke left the graves and burned home behind, gripped his kunai, and walked toward the marked demon despite his injuries.

Ch. 6The first hunt, the tracker in the woods

Uesugi Sasuke followed the system’s red arrow through the night forest, using his new ninja instincts to track a demon despite his broken ribs. He found a demon feeding in a clearing and prepared to assassinate it by striking its neck.

  • Uesugi Sasuke moved carefully through the forest, controlling his breathing and footsteps as he followed the red arrow.
  • Uesugi Sasuke found unnatural footprints and followed their trail toward the sound of a demon eating.
  • Uesugi Sasuke spotted a gray-haired demon feeding on a traveler and judged it to be weaker and less alert than the demon that had attacked his home.
  • Uesugi Sasuke drew two kunai, focused chakra into his limbs, and prepared to kill the demon with a single strike to its neck.

Ch. 7First kill! The value of Revenge Points!

Uesugi Sasuke killed a powerful demon by luring it into a vine trap and earned 100 Revenge Points. He spent all of them to unlock the Fire Release: Great Fireball Technique, and the skill’s knowledge flooded into his mind.

  • Uesugi Sasuke sneaked up on a demon eating a corpse, but his kunai could not pierce its neck and it quickly healed.
  • The demon chased Sasuke through the woods, shrugging off his shuriken as he led it toward a trap he had prepared.
  • Sasuke lured the demon into a falling vine net, leaped above it, and severed its head with a kunai.
  • Sasuke received 100 Revenge Points for the kill and spent them to unlock the Fire Release: Great Fireball Technique.
  • The technique’s hand seals, chakra pathways, and instructions for forming flames surged into Sasuke’s memory.

Ch. 8The Great Fireball's Might, and the Hunger for Power

Uesugi Sasuke tested his newly unlocked Great Fireball Technique and discovered that its immense power nearly exhausted all his chakra. After recovering, he decided to keep hunting demons so he could unlock Chidori and grow stronger.

  • Uesugi Sasuke buried the apothecary and vowed to become strong enough to protect himself and defeat evil demons.
  • Uesugi Sasuke used the Great Fireball Technique at the riverbank and burned trees on the opposite bank to charcoal.
  • Uesugi Sasuke collapsed after the technique drained all his chakra and realized he could only use it as a last resort.
  • Uesugi Sasuke checked the system panel and saw that Chidori required 300 points while Sharingan required 1,000.
  • Uesugi Sasuke resolved to continue hunting demons to earn points and unlock more skills.

Ch. 9Goal: Chidori!

Uesugi Sasuke hunted two demons with traps and earned enough revenge points to unlock Chidori. The chapter ended with him gathering blue lightning in his palm as he began to form the technique.

  • Uesugi Sasuke followed the system's directions to an abandoned village and set traps around a house.
  • Uesugi Sasuke lured a speed-type demon into an animal trap and killed it with his kunai, earning 100 revenge points.
  • Uesugi Sasuke led a powerful demon to a concealed pit trap and killed it after it fell onto sharpened stakes.
  • Uesugi Sasuke reached 300 revenge points and unlocked Chidori.
  • Uesugi Sasuke focused lightning chakra in his palm, producing blue arcs and a sound like birds chirping.

Ch. 10Chidori's Cry and Its Fatal Flaw

Uesugi Sasuke tested Chidori despite the system’s warning that its speed made him unable to see or react along his path. He destroyed a massive rock but nearly crashed into a cliff, leaving him injured and convinced he desperately needed the Sharingan to use the technique safely.

  • Uesugi Sasuke saw the system warn that Chidori was an A-rank assassination technique that required dynamic vision to avoid counterattacks.
  • Uesugi Sasuke dismissed the warning and unleashed Chidori at a massive rock.
  • Uesugi Sasuke lost sight of his path as he charged, pierced the rock, and continued toward a cliff.
  • Uesugi Sasuke stopped himself at the last moment but tumbled to the ground with a badly burned palm and torn arm muscles.
  • Uesugi Sasuke recognized Chidori’s deadly flaw and resolved that he needed the Sharingan.

Ch. 11The System's Plan B: The Path to a Master

After realizing his weak body made Chidori dangerous and his demon victories depended on luck, Uesugi Sasuke accepted the system’s advice to learn Breathing Styles. He set out toward Mount Momoyama to train with former Rumble Hashira Jigoro Kuwajima.

  • Uesugi Sasuke reflected on how his limited chakra, fragile body, and lack of combat fundamentals made his techniques unreliable.
  • The system initiated Plan B and recommended that Sasuke learn Breathing Styles to strengthen his body and improve his energy control.
  • The system identified former Rumble Hashira Jigoro Kuwajima as a suitable teacher and marked Mount Momoyama on Sasuke’s map.
  • Sasuke set aside his pride, accepted the training path, and headed toward Mount Momoyama despite his injured arm.

Ch. 12Mount Momoyama and the Rejected Request

Uesugi Sasuke reached Mount Momoyama and asked Jigoro Kuwajima to teach him a Breathing Style so he could gain strength for revenge. Kuwajima rejected him, leaving Sasuke kneeling in tense silence outside the house.

  • Uesugi Sasuke treated his burned and torn right arm, then followed the system marker toward Mount Momoyama.
  • After traveling through the night and for two days, Sasuke reached the mountain and saw Zenitsu Agatsuma fleeing training while crying.
  • Sasuke knelt before Jigoro Kuwajima and asked him to teach him a Breathing Style so he could take revenge.
  • Kuwajima refused, saying Sasuke’s hatred made his sword too wicked for Thunder Breathing, which was meant to protect life.
  • Sasuke stayed kneeling with his head lowered and his fists clenched as Zenitsu watched from behind a peach tree.

Ch. 13Your sword is too sinister

After Jigoro Kuwajima refused to train him, Uesugi Sasuke revealed his power to prove he was worth teaching. The chapter ended with Sasuke asking whether the real lightning in his hand made him qualified.

  • Jigoro Kuwajima refused to teach Uesugi Sasuke, and Sasuke accepted that he might become a demon to pursue revenge.
  • As Jigoro Kuwajima turned to leave, Uesugi Sasuke stood and proposed a transaction: he would show his power if Jigoro Kuwajima taught him how to fix its flaw.
  • Uesugi Sasuke formed hand seals and summoned a mass of blue lightning in his palm.
  • Zenitsu Agatsuma fell back in fright, while Jigoro Kuwajima recognized the lightning as genuine and was stunned by its power.
  • Uesugi Sasuke presented the lightning without attacking and asked Jigoro Kuwajima if he was now qualified.

Ch. 14A deal struck, a disciple of thunder

Uesugi Sasuke demonstrated his dangerous lightning power to Jigoro Kuwajima to persuade him to teach him Thunder Breathing. Kuwajima agreed under strict conditions, making Sasuke Zenitsu Agatsuma’s junior disciple.

  • Jigoro Kuwajima recognized that Sasuke’s lightning was a dangerous power unlike any Breathing Style and feared Sasuke would destroy himself if left untrained.
  • Kuwajima told Sasuke to put away his lightning, and Sasuke reluctantly dispersed it, weakened but still standing.
  • Kuwajima agreed to teach Sasuke Thunder Breathing, forbidding him from using his power until he could wield a sword and warning that he would stop Sasuke if he turned evil.
  • Sasuke accepted Kuwajima’s conditions with a decisive yes.
  • Kuwajima called Zenitsu Agatsuma over and introduced Sasuke as his junior disciple.

Ch. 15Hellish training and the genius who didn't fit in

Sasuke and Zenitsu began training under Jigoro Kuwajima, where Sasuke excelled at physical endurance but struggled with sword technique. Zenitsu revealed exceptional natural swordsmanship, leaving Sasuke confronted with a talent he could not match.

  • Jigoro ordered Zenitsu to show Sasuke to his room and told them they would train together starting the next day.
  • Jigoro woke both boys before dawn and put them through grueling running, exercises, and sword practice.
  • Sasuke endured the physical training with little difficulty, while Zenitsu collapsed and complained.
  • Jigoro repeatedly criticized Sasuke's stiff, forceful sword swings, then asked Zenitsu to demonstrate the slash.
  • Zenitsu performed a smooth, technically perfect slash, and Jigoro praised his talent while telling Sasuke he could not yet compare.
  • Sasuke stood in silence, gripping his wooden sword as he recognized his defeat in swordsmanship.

Ch. 16Hellish training and a genius who didn't belong

Uesugi Sasuke endured Jigoro Kuwajima’s brutal training but struggled with swordsmanship and the intuitive breathing methods, while Zenitsu Agatsuma displayed effortless talent. After Sasuke failed to sense the power of Thunder Breathing and witnessed a faint spark around sleeping Zenitsu, he felt more keenly that he was an outsider in this world.

  • Uesugi Sasuke and Zenitsu Agatsuma endured Kuwajima’s punishing daily training of weighted runs, conditioning exercises, and thousands of sword swings.
  • Kuwajima repeatedly criticized Sasuke’s stiff swordsmanship and praised Zenitsu’s natural coordination, stirring jealousy in Sasuke.
  • After Sasuke completed five thousand swings, Kuwajima ended the physical training and began teaching the fundamentals of Thunder Breathing.
  • Sasuke struggled to understand Kuwajima’s instructions through bodily sensation, while Zenitsu fell asleep during the breathing exercise.
  • Zenitsu unconsciously exhaled in his sleep, and Kuwajima and Sasuke sensed a faint flicker of electricity around his hair.
  • Sasuke looked at Zenitsu and felt like a lonely outsider who did not belong, driven by his desire for revenge.

Ch. 17Zenitsu's talent and Sasuke's confusion

Sasuke struggled to learn Thunder Breathing while Zenitsu demonstrated its speed instinctively in his sleep. After Kuwajima told Sasuke to listen to thunder rather than control it, Sasuke ended the chapter determined to force thunder to obey him by his own methods.

  • Sasuke brooded over Zenitsu's unconscious flash of Thunder Breathing and envied his talent.
  • Kuwajima taught Sasuke and Zenitsu Total Concentration Breathing and demonstrated Thunderclap and Flash.
  • Sasuke copied Kuwajima's stance and analysis but failed to produce the technique's explosive speed.
  • After thunder frightened Zenitsu unconscious, Zenitsu instinctively performed Thunderclap and Flash, moving five meters before collapsing.
  • Kuwajima explained that Zenitsu's body remembered thunder's rhythm while Sasuke's overthinking held him back, and told Sasuke to learn to listen.
  • Sasuke practiced alone that night, then resolved to force thunder to make the sound he wanted.

Ch. 18Thunder Breathing, First Form

Uesugi Sasuke tried to master Thunder Breathing through analysis and relentless physical training, but his precise movements could not reach the speed of thunder. After hitting an invisible limit, he realized he might use Thunder Breathing as a trigger to unleash his chakra, and prepared to test that idea.

  • Uesugi Sasuke spent the night mechanically practicing Thunderclap and Flash, while Jigoro Kuwajima watched and recognized that Sasuke’s movements lacked life.
  • Zenitsu Agatsuma found Sasuke still training at dawn, became frightened by his intensity, and fled back to his room after Sasuke told him to scram.
  • Uesugi Sasuke increased his training with weighted laps, squats, and jumps, but his muscular speed still fell short of Thunderclap and Flash.
  • After a failed sprint, Uesugi Sasuke realized that Breathing Styles could serve as a switch to overclock his body and considered using one to ignite his chakra.
  • Uesugi Sasuke picked up a broken wooden sword and resolved to use Thunderclap and Flash as the trigger for his Ninjutsu.

Ch. 19Chakra and Breathing Styles, a Failed Fusion

Uesugi Sasuke tried to combine Thunder Breathing with lightning release chakra, but the powers violently clashed and left him badly injured. As he recovered, he wondered whether Breathing Styles should support chakra rather than fuse with it.

  • Uesugi Sasuke realized that a Breathing Style could act as a switch to unleash his body's potential and decided to make it serve his chakra.
  • Uesugi Sasuke used Thunder Breathing and channeled lightning release chakra into his legs before attempting Thunderclap and Flash.
  • Uesugi Sasuke's chakra and the power drawn out by Thunder Breathing clashed, causing severe pain and sending him crashing into a tree.
  • Uesugi Sasuke lay injured and questioned why the powers repelled each other despite their similar nature.
  • Uesugi Sasuke wondered whether a Breathing Style was meant to support chakra instead of being fused with it.

Ch. 20Reverse thinking, Sharingan, awaken!

After his failed attempt to fuse Breathing Style and chakra, Uesugi Sasuke realized breathing could trigger and control his chakra instead. He created a powerful new technique, unlocked the One-Tomoe Sharingan, and prepared to test his combined abilities against a demon.

  • Uesugi Sasuke reconsidered his failed fusion attempt and concluded that Breathing Style could serve as a trigger for chakra rather than a source of energy.
  • He synchronized his breathing with compressed lightning-release chakra and used the resulting technique to destroy a large boulder with little strain.
  • A system message rewarded Sasuke for achieving a preliminary fusion of power systems by unlocking the One-Tomoe Sharingan.
  • Sasuke awakened the Sharingan and discovered that it let him see movement and fine details with extraordinary clarity.
  • Sasuke realized the Sharingan could address Chidori's flaw and looked forward to testing his combined powers on a demon.

Ch. 21Scarlet eye, stunned master and disciple

Uesugi Sasuke awakened his Sharingan after a breakthrough in strength and discovered its heightened perception. He told Jigoro Kuwajima it was his family’s Kekkei Genkai, while Zenitsu Agatsuma panicked at the sight of Sasuke’s red eye; Sasuke then walked off to train.

  • Uesugi Sasuke opened his newly awakened Sharingan and saw the world in extraordinary detail, including the slowed movements of a flying insect.
  • Jigoro Kuwajima sensed Sasuke’s unsettled aura, saw his red eye, and worried that he had been injured.
  • Uesugi Sasuke told Jigoro Kuwajima that his eye was a hereditary Kekkei Genkai that awakened with a breakthrough in strength.
  • Zenitsu Agatsuma saw Sasuke’s eye, screamed that he was a monster, and hid behind Jigoro Kuwajima.
  • Uesugi Sasuke closed and reopened his eye, making it look black again, then walked alone toward the training posts.

Ch. 22The Power of Insight: Seeing Through Thunderclap and Flash

Sasuke used his Sharingan to analyze Jigoro Kuwajima’s Thunder Breathing demonstration and reproduced its power-gathering stance perfectly. Kuwajima recognized Sasuke’s ability to see through and copy what others had mastered, while Zenitsu was left shaken by the gap between them.

  • Zenitsu avoided Sasuke during the morning and struggled to understand Kuwajima’s lesson on generating power through the waist and abdomen.
  • Sasuke activated his Sharingan and analyzed the muscles, breathing, and energy pathways involved in Kuwajima’s Thunder Breathing demonstration.
  • Sasuke asked to try and reproduced the First Form’s opening stance and power-gathering technique after studying it once.
  • Zenitsu stared in disbelief as Sasuke demonstrated a technique he had failed to learn despite extensive practice.
  • Kuwajima called Sasuke’s performance very good and suspected that Sasuke’s eyes had let him see through and plunder the master’s knowledge.

Ch. 23The perfect Chidori, the return of thunder

Sasuke combined Thunder Breathing, chakra, and his Sharingan to perfect Chidori and destroy the boulder that had defeated him before. Zenitsu watched in terror, while Jigoro recognized that Sasuke had created a technique unlike any Thunder Breathing he had taught.

  • Sasuke went to the waterfall to confront his earlier failure with Chidori, followed secretly by Zenitsu as Jigoro watched from the slope.
  • Sasuke used a Thunder Breathing stance and his Sharingan to control and compress the lightning in his palm.
  • Sasuke charged the boulder and pierced it with Chidori, keeping his movement under control.
  • The boulder fractured and crumbled into powder, leaving Sasuke unharmed and Zenitsu speechless with fear.
  • Jigoro recognized Sasuke's attack as a new, exceptionally efficient killing technique and returned to the wooden house.

Ch. 24A Master's Worries, a Swordsman's Soul

Jigoro Kuwajima worried that Uesugi Sasuke’s power was driven by vengeance and that he had nothing to protect. After Sasuke rejected the idea of protecting others, Kuwajima halted his Breathing Style training and assigned him a thousand sword swings a day until he understood why he wielded his sword.

  • Jigoro Kuwajima watched Uesugi Sasuke practice chakra control in the courtyard and invited him inside for tea.
  • Kuwajima told Sasuke about Demon Slayer Corps comrades who had died protecting others despite their weakness.
  • Sasuke said the comrades would not have died if they had been strong enough, and Kuwajima replied that their swords had souls.
  • Kuwajima asked what Sasuke would do after killing all the demons, leaving Sasuke unable to answer.
  • Kuwajima told Sasuke that a swordsman needed something to protect, but Sasuke said he had nothing.
  • Kuwajima stopped Sasuke’s Breathing Style training and ordered him to swing his sword one thousand times each day until he understood his purpose.

Ch. 25A spar between fellow disciples, suppressed talent

Uesugi Sasuke endured sword drills before Jigoro Kuwajima ordered him to spar with Zenitsu Agatsuma. After Sasuke repeatedly knocked Zenitsu down, Zenitsu unconsciously unleashed the beginnings of Thunderclap and Flash, leaving Sasuke with a bloody scratch and a new respect for his hidden ability.

  • Uesugi Sasuke and Zenitsu Agatsuma practiced sword swings from sunrise to sunset under Jigoro Kuwajima's instruction.
  • Jigoro Kuwajima ordered Sasuke and Zenitsu to spar, and Zenitsu reluctantly faced Sasuke.
  • Sasuke easily dodged Zenitsu's clumsy attacks and knocked him down repeatedly.
  • After Zenitsu collapsed, Sasuke noticed his breathing change and saw him rise into the opening stance of Thunder Breathing.
  • Zenitsu vanished with a burst of speed and nearly struck Sasuke, who dodged but received a shallow scratch on his cheek.
  • Zenitsu collapsed unconscious, and Sasuke wondered about the power hidden inside him.
Arc 1 of 13