Sanemi Shinazugawa

He is a man of average height, with light skin and gray eyes. He has a sharp look and no eyebrows, his hair color is a warm gray which he keeps short. Having his bangs divided parallel to his forehead into two thick strands, one in the center and the other on the left side of his head. One of Sanemi's most prominent features is his remarkable physique and the numerous scars that mark his face, chest and arms, which he does not hide and maintains as a reminder of how hard his job is, of which he feels proud. Regarding his clothing, this consists of the Demon Hunters' uniform, with the upper part unbuttoned, exposing his torso and his multiple scars. He also has a white jacket, as well as keeping his Nichirin sword on his belt. The latter in turn holds his Hakama which remains attached to each of his ankles thanks to two pairs of thick straps. Later between the arcs of the Functional Recovery Training Arc and the Pillar Training Arc, Sanemi cut his hair, leaving only the center bangs.

He is usually extremely impulsive, aggressive and violent when confronting a Demon. He is always willing to take risks thanks to his reckless attitude, but Kagaya Ubuyashiki is the only person with whom he does not have that kind of attitude. Well, he has deep respect for him. These attitudes as well as his coldness come as a result of a tragedy that occurred in his childhood, which is why he detests all types of demons. Contaminated by that pain, he became a difficult person to dissuade after making a decision. This also caused him to show an abusive attitude towards his brother in the future, pretending to harbor great hatred towards him when that was not really the case.

Sanemi was the eldest of seven children born in a dysfunctional home, with a father who was extremely abusive towards him, his mother and his seven siblings (Genya included) whom he beat continuously and for no reason, until one day, someone who had a grudge against His father stabbed him to death.

One day, Sanemi's mother failed to return home, so a worried Sanemi went looking for her. At some point, he found her and realized that she had become a Demon, but he was unable to stop her from returning home and killing five of his siblings. However, just before he could kill Genya, Sanemi threw her out of the window onto the street below while armed with a knife. In the ensuing fight, she wounded him, leaving two large scars on his face, and her marechi blood, which disorients Demons and makes them intoxicated, gave him an opening to cut her.

When Genya goes outside to find a doctor for her severely injured siblings, she finds Sanemi with her dead mother at his feet. Panicking, and unaware that the "wolf" that attacked them was her mother transformed into a Demon, Genya screams and accuses Sanemi of having murdered her. [4] Seeing this, Sanemi goes into shock, suffering from Achromatopsia while her mother's body begins to disintegrate upon contact with the first rays of the sun.

Following that tragic event, Sanemi abandons his brother and sets out to hunt Demons on his own in a suicidal manner. Without the knowledge of Demon Slayers or Nichirin Swords, he instead armed himself with a multitude of weapons and fought Demons at night, incapacitating them until the morning sun killed them. Despite this crude and reckless battle style, he managed to survive thanks in part to sheer luck and the unique scent of his blood.

While wandering, he came across a legitimate Demon Slayer; his name was Masachika Kumeno, who helped him and introduced him to a suitable trainer. Upon completing their training, they teamed up to defeat the then Lower Moon One of the Twelve Demon Moons. However, Kumeno lost his life in the battle, and only Sanemi was promoted to the rank of Wind Pillar.

By the time of their promotion, Gyomei Himejima, Kanae Kocho, Tengen Uzui and Giyu Tomioka were already mainstays.

Embittered by Kumeno's death, Sanemi becomes enraged at Kagaya, accusing him of calmly giving orders from above while sending hundreds of Hunters to their deaths for his cause. To his surprise, Kagaya takes the criticism gracefully before mentioning Kumeno by name; Kanae then informs him that Kagaya has memorized the names and backgrounds of every Hunter who has died since he became leader. This discovery, and reading Kumeno's will given to him by Kagaya, gives Sanemi a newfound respect for the Demon Extermination Corps leader.

To Kokushibo, after he identifies Sanemi as the Pillar of Wind) "You're right. I am the wind that will blow your head off, bitch."
(To Genya Shinazugawa) "I'm serious, you really are a pathetic little brother. Why do you think I went so far as to kill our own mother? Because I wanted to protect you! Bastard, you should have gotten married, had some damn kids, and lived until you were a fucking old man. For all the times we couldn't do anything for mom, and for all the times we couldn't do anything for our little sisters, you should have... had a wife and kids that were as damn happy as they should have been. Because I would have made sure that no demon would ever target you."

The relationship between Sanemi and Genya took an unexpected turn when Genya made the mistake of calling his brother a murderer for defending himself and ending the life of his mother, who had become a demon on what was the most complicated night for the Shinazugawa brothers.

From that moment on, Sanemi and Genya began to grow increasingly distant. Genya regretted inwardly having called Sanemi a murderer at a time when the latter was particularly emotionally fragile. To top it off, Sanemi's character became much sourer, he began to hate Muzan's demons more and more and tried to convince Genya that he was not talented enough to become a demon hunter like him. Sanemi also burst into anger when he learned that Genya had started eating demons to become more powerful.
It is at this point that we must move on to chapter 166 of the manga. It is revealed in it that Sanemi does not actually hate his brother, he simply wanted him to live a quiet life and raise a family while he took care of defeating Muzan. Because of this, Sanemi also underestimated Genya's abilities as a Demon Slayer several times. His idea was to discourage his brother until he made the decision to leave the Demon Extermination Corps on his own.