Even so, because Tanjiro can technically use two breathing styles and Genya can use none, we've got our money on Tanjiro winning.
Demon Consumption & Empowerment: Genya possesses unnaturally strong jaws and special digestive organs which allow him to tear off and consume the flesh of demons without any adverse effects. By devouring demon flesh, Genya gains demonic characteristics, such as fangs, dark sclera, and unique yellow tips in his hair.
Going beyond this, Giyu is one of the most combat proficient Demon Slayers seen throughout the entire series. Furthermore, his strength and abilities are always portrayed as seemingly a cut above the rest of the Hashira, solidifying his expected victory against Tanjiro.
Genya was sliced up by Kokushibo, but the consumption of his hair allowed him to regenerate immediately.
Without her last-ditch efforts, Tanjiro would have remained a demon and could have caused a ton of problems to the demon hunters around him. Despite all of these, Sanemi's raw power and speed are far higher compared to hers, which means that he can beat her with ease.
Can 13th form Tanjiro beat Sanemi? Sanemi WOULD win but it would be at high or extreme def considering how far Tanjiro has developed as a Demon Slayer . People are vastly underestimating Sanemi just because he wasn't able to last longer against Muzan or deal as much damage to him as Tanjiro did.
If Sanemi had been the one to encounter Akaza, while he surely would've given a better fight than Rengoku did, Sanemi probably wouldn't have emerged victorious regardless of Akaza's handy Compass Needle that makes him nearly impossible to decapitate anyway.
But Genya is not weak. Rengoku Senjuro once said, in order for the Japanese sword to change color, the swordsman must reach a certain level of swordsmanship.
In the simplest terms, the reason that Genya can't use Breathing Styles stems from his inability to achieve the total concentration breathing that other demon slayers use in order to access their abilities.
With his signature double-barreled shotgun, he is stated to be a unique combatant. The bullets of the shotgun are made of the same ore as Nichirin Blades. Although, if Genya had to fight Zenitsu, he would lose miserably as the latter can dodge bullets with his speed and reflexes.
So to compare Tanjiro's Demon form in which he's immune to sunlight, and also has the prowess of Sun Breathing, it would give him an upper hand, but still he would lose to Yoriichi.
After awakening his demon slayer mark, Giyu greatly overpowers Akaza. However, he is able to keep up with the fight only because of Tanjiro. If Giyu had soloed against Akaza, he would have died.
Genya also possesses “Demonic Transformation”, where he temporarily gains demonic attributes by consuming the live flesh of a demon. He can gain regeneration and physical strength equal to the demon he is consuming the flesh of.
Genya is always angry at others because of everything he has gone through in his early life. Every waking moment is an attempt to become stronger, even if it is at the expense of his life. He is doing this only for his brother to acknowledge him.
Demon Slayer: Kimetsu No Yaiba, Volume 20 continues as the Demon Slayer Corps' initial confrontation with the most powerful of Muzan's demons, Kokushibo, has left Tokito severely wounded and Genya cut in half.
Genya remains loyal to the Darkling, but his nichevo'ya mutilate her when she betrays him to help Alina escape in Siege and Storm. She joins Alina and helps in taking the King down. She marries David Kostyk and becomes a member of the Grisha Triumvirate.
As the Upper Moons pose a grave threat, Genya's demon abilities prove crucial in the battle. But behind his determination to become a Hashira lies a tragic past that drives him to seek redemption and reconciliation with his brother, Sanemi Shinazugawa.
For the book character, see Genya Safin. Genya Safin is a Tailor for the Queen of Ravka who was tasked with spying on Alina Starkov and poisoning the King.
Inosuke is extremely fast and his aggressive fighting style combined with his breathing techniques makes him extremely strong. Genya will be unable to enhance his physical abilities since he is not fighting against a demon. Inosuke will be able to beat Genya with ease.
The actual answer is a little more complicated, but essentially no, Genya is not a demon. According to the source manga: "Genya has a special ability. For a short amount of time, he can become a demon using his bite strength and his special digestive organs."
Genya Safin is a Tailor, a hybrid Grisha who has the power to alter people's appearances. Because of her unique gifts she has been placed in service to the Queen of Ravka, a situation that has isolated her from other Grisha and made her an outcast among her own people.
Sanemi's sheer power and speed will be able to overwhelm Nezuko even in her final form. Nezuko's Blood Demon Art would not work against Sanemi since he's a human, and he has the ability to decapitate her head if he wanted to.
While Sanemi and Giyu are pretty evenly matched, it's possible Sanemi would win a fight between them based on his ruthless nature alone. Giyu has shown mercy, but Sanemi isn't the type to hold back for any reason.
1) Gyomei Himejima
He, along with Sanemi Shinazugawa were able to beat the Upper Moon 1, Kokushibo. The demon was in awe of Gyomei's physique and declared him to be the strongest Demon Slayer he had faced in 300 years.