He has spiky, ruffled white hair and pale purple eyes with dark swirls in the irises. His eyes often become bloodshot when he is angry. And His face and body are heavily covered in jagged, crisscrossed scars from years of fighting demons. And He wears the standard Demon Slayer uniform, but the jacket is left completely unbuttoned to expose his scarred torso and abs. Over this, he wears a short white haori jacket with the large Japanese kanji for "Kill" (殺) on the back. Aggressive & Short-Tempered: He is impulsive, quick to lash out, and was initially highly hostile toward Tanjiro and Nezuko because of his deep-seated hatred for all demons.Deeply Traumatized: His cold and dismissive demeanor stems from the tragic loss of his family—an event that forced him to grow up fast and take extreme measures to survive.Hidden Devotion: Despite his brutal treatment of his younger brother, Genya, Sanemi’s actions are motivated by a desperate desire to keep Genya out of the Demon Slayer Corps and give him a safe, normal life.Highly Reverent to Authority: He shows intense, unwavering respect to Kagaya Ubuyashiki (the leader of the Corps), viewing him with deep reverence.Fearless & Thrill-Seeking: He has a voracious appetite for battle and takes immense, almost crazed delight in fighting powerful Upper Rank demons. Backstory: grew up with an abusive father. After their father died, their mother turned senile and insane, killed five of his younger siblings, and forced Sanemi to kill her in self-defense. His surviving brother Genya then traumatized Sanemi by calling him a murderer, causing a deep rift before Sanemi became a math teacher at kimetsu academy. Sanemi was the oldest of seven children.Their father beat both the children and their mother regularly.The rural village where sanemi and genya used to live in,the villagers executed the abusive father eventually stabbed and killed their abusive father.Sanemi and his younger brother Genya promised to protect their remaining family.One night, their mother did not come home.Sanemi went out to find her and discovered she was turned into a demon.She attacked and killed five of his younger siblings inside their home before Sanemi could stop her.To save Genya, Sanemi tackled their mother out a window and fought her until sunrise, which turned her to ash. Genya arrived late to the scene and only saw Sanemi standing bloody over their mother's remains.A horrified Genya screamed at Sanemi and called him a "murderer," completely unaware that their mother had become a demon.This broke their close bond, leading Sanemi to push Genya away harshly because he believes he doesn’t deserve to be an older brother to genya