Yoriichi

Biodata

Feature	Details
Name	Tsugikuni Yoriichi (缘一)
Alias(es)	Founder of Breathing Styles; the “ceiling” 4 20 199 244
Species/Race	Demon (formerly human) 34 35
Gender	Male
Affiliation	Demon Slayer Corps (former); associated with Muzan Kibutsuji and the Infinity Castle demons after becoming a demon 21 32 34
Occupation/Role	Swordsman; creator and teacher of Breathing Styles 20 32 199
Status	Active 262
First Appearance	Chapter 14: “Tsugikuni”

Power Progression

Stage / Realm / Level	Chapter	Notes
Clear World	20	Already possesses the Clear World, granting heightened perception and control; explains its principles to Muzan.
Sun Breathing / Thirteenth Form	20	Reveals Sun Breathing while sparring Muzan and spontaneously creates the Thirteenth Form under pressure.
Scarlet Traces and Crimson Blade	25	Uses the Transparent World, Scarlet Traces, and a crimson Nichirin Blade to overwhelm a regenerating demon.
Demon transformation	34	Muzan injects blood into Yoriichi’s head, turning him into a demon and restoring his altered memories.
Constant Crimson Blade	91	Demonstrates the ability to keep his Crimson Blade active continuously, even while unarmed.

Background / History

Yoriichi was born into the Tsugikuni samurai family and was neglected by his cold father. As a young child, he secretly watched his elder brother Michikatsu train and supported his ailing mother, Aka no Hana. Muzan learned of Yoriichi’s existence when he was four or five years old and began monitoring him out of fear of his future potential. 14

At seven, Yoriichi left the Tsugikuni household with dried food, a knife, and the bamboo flute given to him by Michikatsu. During his travels he met Uta, and the two chose to remain together. 15

After Half-Demons attacked them, Muzan captured Yoriichi and Uta and brought them to Uta’s home. Though Yoriichi initially regarded Muzan as an enemy and tried to protect Uta, the children eventually lived under Muzan’s supervision, studying, copying books, and practicing swordsmanship. 16 18 19

Yoriichi developed his own sword techniques without formal instruction, mastered the Clear World, and awakened Sun Breathing. He later asked Muzan’s permission to join the Demon Slayer Corps so that he could protect people from Half-Demons. 17 20 21

A demon’s explosion briefly affected Yoriichi’s mind during a joint mission with Kokushibo. Its Blood Demon Art altered his memories, leaving him unable to recognize Muzan and compelling him to attack him as the Demon King. After returning to the Corps and recounting his version of events, Yoriichi was expelled. 27 29 32

Following his expulsion, Yoriichi lived with the Kajimon family and taught the Kamado family Sun Breathing as the Dance of the Fire God. 32

Muzan eventually turned Yoriichi into a demon by forcing his blood into Yoriichi’s head. The transformation restored Yoriichi’s memories; he apologized to Muzan, while continuing his peaceful life with Uta. 34 35

More than forty years later, Uta died of old age after refusing Muzan’s offer of demonhood. Grieving, Yoriichi accepted Kokushibo’s challenge to spar and instantly defeated him with Sun Breathing’s Thirteenth Form. 36

Appearance

Yoriichi is usually expressionless, with black hair tied in a high ponytail, red pupils, yellow clothing, a red haori, flower-patterned earrings, and a sword at his waist. In a later encounter with the parallel-world Muzan, he is described with long red hair. 29 255

• Wears distinctive flower-patterned earrings associated with Sun Breathing. 29 32
• Carries a Nichirin Blade, typically kept ready even during tense conversations. 29 199
• Maintains an intimidatingly calm, unreadable expression in combat. 262

Personality

Yoriichi is quiet, restrained, and deeply protective of those close to him. As a child, he tried to shield Uta from Muzan despite being powerless against him; later, he repeatedly prioritized Kokushibo’s safety during missions and battles. 16 24 26

He values ordinary happiness over power. After Uta’s death, he reflects that he has experienced more happiness than he feels he deserved, but accepts Muzan’s advice not to dwell on it. 36

Despite his instinctive hostility toward Muzan and his duty as a Demon Slayer, Yoriichi recognizes Muzan’s past care for himself and Uta. He remains conflicted rather than wholly hateful after recovering his memories. 18 34 245

Abilities & Skills

Sun Breathing

Yoriichi is the creator and foremost user of Sun Breathing, the original Breathing Style. His attacks generate intense heat and sun-like radiance capable of severely damaging demons. 20 199

• Created the Thirteenth Form during a spar with Muzan. 20
• Beheaded a powerful regenerating demon with Sun Breathing during the Riverview Town mission. 25
• Instantly defeated Kokushibo in a later spar with the Thirteenth Form. 36
• Taught the Kamado family the style as the Dance of the Fire God. 32

Clear World

The Clear World grants Yoriichi extraordinary perception, bodily control, and the ability to identify an opponent’s weaknesses and movements. 20

• Allows him to perceive Muzan’s abnormal internal structure. 18
• Lets him pursue Muzan across great distances after he escapes. 29
• Does not directly strengthen the user’s body; its value lies in perception and technical mastery. 20

Scarlet Traces and Crimson Blade

Yoriichi can activate Scarlet Traces and turn his Nichirin Blade crimson, dramatically increasing its effectiveness against demons. 25

• Combined the Crimson Blade, Scarlet Traces, and Transparent World against a regenerating demon. 25
• Can maintain a Crimson Blade even without carrying a weapon beforehand. 91
• His thrown Nichirin Blade carries enough force to pierce walls and damage the Infinity Castle’s flooring. 92

Demon Physiology

After Muzan transforms him, Yoriichi gains demonic longevity while retaining his swordsmanship and memories. 34 35

• Muzan’s blood restores Yoriichi’s altered memories during the transformation. 34
• Continues using a Nichirin Blade and Sun Breathing despite being a demon. 36 244
• Remains feared by the parallel-world Muzan, whose survival instinct drives him to self-destruct and flee rather than face Yoriichi. 255 256

Swordsmanship

Yoriichi is an innate swordsman who develops techniques independently and can overwhelm opponents with overwhelming speed and precision. 17 27

• Fought Muzan with attack speed great enough to leave him struggling to evade. 29
• Used an axe to sever multiple whip-like appendages from Muzan despite lacking his sword. 34
• Easily repelled two hundred demons barehanded during a forced blood battle. 91

Equipment / Weapons / Items

• Nichirin Blade — Yoriichi’s primary weapon and the conduit for Sun Breathing and his Crimson Blade. 25 36
• Flower-patterned earrings — A personal accessory later passed to the Kamado family’s child. 29 32
• Bamboo flute — A treasured gift from Michikatsu that Yoriichi keeps into adulthood. 15 22 199

Relationships

• Muzan Kibutsuji — Captor, guardian, and self-proclaimed adoptive father. Muzan raised Yoriichi and Uta for five years, while Yoriichi’s memories and instinctive mission repeatedly complicate their bond. 16 21 29 34
• Tsugikuni Kokushibo / Michikatsu — Elder brother. Yoriichi admires and worries for him despite Michikatsu’s jealousy, demonic transformation, and rivalry. 22 23 26 36
• Uta — Wife and childhood companion. Yoriichi protects her from danger, shares a peaceful human life with her, and mourns her death decades later. 15 16 35 36
• Kajimon Tanki — Close friend and fellow charcoal worker after Yoriichi’s expulsion from the Corps. 32 34
• Kamado family — Recipients of Yoriichi’s Sun Breathing, preserved by them as the Dance of the Fire God. 32
• Tanjiro Kamado — Descendant of Yoriichi’s successor line and a later Sun Breathing user. Yoriichi tests Tanjiro’s strength and approves of his resolve. 244 245

Story Role / Major Arcs

Childhood and Muzan’s Household

Yoriichi leaves the Tsugikuni family, meets Uta, and is brought under Muzan’s care after their encounter with Half-Demons. His earliest training reveals his unmatched natural talent and latent hostility toward Muzan. 15 20

Demon Slayer Corps and Memory Alteration

Yoriichi joins the Demon Slayer Corps to fight Half-Demons, works alongside Kokushibo, and develops a stronger bond with his brother. A demon’s explosion alters his memories and causes him to turn against Muzan, culminating in his expulsion from the Corps. 21 32

Demon Transformation and Life with Uta

After living with Uta and the Kajimon family, Yoriichi is forcibly transformed into a demon by Muzan. His memories return, and he continues living with Uta until her natural death decades later. 34 36

Battle with Tanjiro

During the large-scale conflict involving the Twelve Kizuki and Demon Slayers, Muzan throws Yoriichi toward Tanjiro. Rather than immediately kill him, Yoriichi recognizes Tanjiro’s connection to the Sun Breathing legacy and challenges him to demonstrate his strength. 244 245

Parallel-World Muzan Incident

Yoriichi confronts a parallel-world Muzan known as the Scum Boss. His presence terrifies the other Demon King so severely that the latter repeatedly self-destructs, flees, and disguises himself to avoid Yoriichi. 255 256 260 262

Notable Quotes

“Let me see your strength.” — Yoriichi to Tanjiro 244

“Who cares if you were supposed to have it or not? As long as you're happy, that's all that matters.” — Muzan to Yoriichi 36

Trivia

• Muzan considers Yoriichi his adopted son and repeatedly demands to be called “Dad,” but Yoriichi never complies. 77 247
• Muzan’s fear of Yoriichi predates their first meeting; he seeks out the Tsugikuni family specifically because he remembers Yoriichi as a future threat. 14
• Although he is a demon, Yoriichi continues to wield a Nichirin Blade and use Sun Breathing. 36 244