Sanemi is a tall man, only little taller than Giyu Tomioka, and is muscular and slender. He has large eyes, scar’s all over his face and chest, a result from fights with demons and the fight with his mother, and silver hair. He cut this hair short somewhere in between the Functional Recovery Training Arc and the Demon Train Arc.
Sanemi has a hot blooded and resilient personality as demonstrated by his impulsive actions and lack of or empathy. When he is first introduced, Sanemi immediately distrusts Tanjiro's explanation for Nezuko's presence, insulting him before stabbing through the box with Nezuko inside.
He shows little to no respect to any other individuals except for Kagaya Ubuyashiki whom he speaks to with manners and respect. Despite his nature, Sanemi has a strong resolve and stands up for what he believes in even if it means he must oppose the actions of his own surviving family members.
It was later revealed during his battle with Kokushibou that behind his rough and rude attittude, Sanemi still cares for his younger brother and actually want Genya to live a normal life, had Genya didn't choose to join Demon Slayer. He becomes enraged to Kokushibou for literally maiming his brother in half.
Sanemi was raised as the eldest son of 7 children and lived with both of his parents. He grew up in an abusive household with his father constantly lashing out at all the children as well as Sanemi's mother until he was ultimately stabbed and killed at random.
One day, Sanemi's mother did not return home when expected leaving the children to worry on her whereabouts. Just when Sanemi was about to set out to look for her, a loud banging sound was heard at the door. The children opened it only to be immediately slaughtered by their mother who had transformed into a demon. In order to protect his siblings, Sanemi tackled his mother out of the home and left his younger brother Genya to care for the siblings.
Having settled the injured children in the home, Genya frantically set out to find a doctor to care for the kids. Upon setting out, Genya discovers Sanemi in the middle of the path with his mother lying dead at his feet. Genya screams out at Sanemi calling him a 'murderer' and angrily accusing him of murdering their mother. 
Later it was revealed that upon killing his mother during that night,Sanemi had lost the ability to see and perceive color,seeing everything in black and white and making it difficult to see at night, likely due to the psychological trauma from killing his mother and being disowned by his brother, now distraught and in pain due to these events Sanemi began to hunt demons on his own with suicidal devotion, having no idea about Nichirin Blades. He instead armed himself with a mountain full of weapons and began to battle demons on his own, where he then resorted to a crude method of killing demons, where he would first incapacitate and capture the demon and then wait for morning to come, where he would then proceed to then string up his captured demon and let the sun destroy them. Despite this crude and reckless battle style he managed to survive and kill several demons, later upon looking back at his past exploits Sanemi admitted that the only reason why he survived was due to sheer luck and the unique aroma of his blood that caused the demons to become intoxicated, drunk and less focused in their battles and later acknowledging that his past actions were likely his attempts at suicide, but before he could be killed due to his reckless hunts. He meet a Legitimate Demon Slayer named Masachika Kumeno, who later helped him and introduced him to a proper trainer and upon his completion of his training, proceeded to then teamed up together with him in order to defeat one of the Twelve Demon Moons, more specifically the then Lower Moon One, where Kumeno then lost his life in battle and leaving Sanemi as the only survivor, where he was then promoted to the upper ranks of the Demon Slayer Corps and was given the rank and title of the Wind Pillar.
Abilities and Powers
Sanemi's skills and sword techniques are incredibly powerful and refined,with him being able to fight and contend with Kokushibo,a thousand year old demon with hundreds of years of skill and experience who also complemented that his physical abilities and techniques have already reached their peak.
Breath of Wind Style (
- First Style: Dust Whirlwind Cutter (
壱ノ 型 鹿 旋 風・ 削ぎ Ichi no kata: Jin senpū・sogi?): Sanemi dashes forward in a cyclone of slashes.
- Second Style: Claws-Purifying Wind (
弐ノ 型 爪 々・ 科 戸 風Ni no kata: Sōsō - shina to kaze?): Sanemi sweep onward and creates four claws-like slash to enemy.
- Third Style: Clear Storm Wind Tree (
参ノ 型 晴 嵐 風 樹San no kata: Seiran fūju?): Sanemi sweep his sword in circular movements to redirect enemy attacks.
- Fourth Style: Rising Dust Storm (
肆ノ 型 昇 上 砂 塵 嵐?, Shi no kata: Shōjō sa jinran): Sanemi sweep his sword horizontally and create multiple cyclone of slashes to deflect enemy attacks.
- Fifth Style: Winter Gale (
伍ノ 型: 木 枯らし 颪Go no kata : Kogarashi oroshi?) - Sanemi strikes from above while falling in a multitude of arced slashes.
- Sixth Style:Black Wind Mountain Mist- Sanemi unleashes a powerful vertical side way slash upwards at his target.
- Seventh Style: Tengu Squall
- Intoxicant Blood (Marechi) - Sanemi's blood was revealed to be one of the rarest blood types making it incredibly intoxicating and mouth watering to demons. It is also unique due to it intense potency that the smallest whiff of his blood immediately causes demons to salivate and lose focus, it was even able to affect the strongest of the Upper Moon Demons, Kokushibo.
- Muscle Control - Sanemi has also shown the ability to manipulate his own muscles to close up and prevent fatal and mortal wounds from opening up and bleeding out during mid battle, as seen when he was fatally slashed and cut up by Kokushibo, he was still able to fight on by manipulating his own muscles to close up his wounds.
- Demon Slayer Mark - Later during battle against Upper Moon One, Kokushibo, Sanemi awakened his own Mark that takes on the appearance of Paper Oragami Windmill with two dots on both sides on his left cheek,that dramatically increases his power and abilities,as seen that despite being grievously injured and slashed across his abdomen Sanemi was still able to fight and contend with Kokushibo on even ground,showing that his physical endurance,strength and tolerance to pain have been increased dramatically.
- Sanemi was ranked in 15th place as of the first character popularity poll with 207 votes.
- As stated by Giyuu, Sanemi has a love of ohagi, and he frequently cooks it. However his pride refuses him from saying anything about it.
- Similar to Kiyoshi, Sanemi is a marechi, and his blood is considered even rarer for a marechi as it can intoxicate demons and disrupt their senses and movement speed.