Rengoku hasn't yet awakened his Demon Slayer Mark since he didn't survive that long against Akaza. In case you didn't know, Demon Slayer Mark dramatically boosts a demon slayer's strength, speed and senses.
7/10 Did Not: Kyojuro Rengoku Died Before Others Manifested Their Marks. Kyojuro was the first Hashira to die at the hands of an Upper Moon demon, due to an unfortunate encounter with Akaza.
Rengoku was more powerful than two pillars with the access to the demon mark. This implies that if he had access to the demon mark, his physical abilities would dramatically increase, certainly making him stronger than Sanemi and possibly making him stronger than Gyomei.
Patterns that resemble clouds which appear on both sides of his cheeks and one on the left side of his forehead.
Well, Rengoku was already able to nearly defeat Akaza as he was. Akaza is too powerful. He wasn't going hard on Rengoku in the MT Arc.
While Mist Breathing has six forms, he created a Seventh Form: Obscuring Clouds during the fight with an Upper Rank Demon. Muichiro can defeat Akaza easily with his petite body that leverages his speed. Moreover, his ability of Transparent World can aid him in landing a fatal blow on Akaza's weak spot.
At the end of the day, none of the Hashira could've defeated Akaza – even though a few of them could've succeeded in decapitating him.
Ninth Form: Rengoku ( 玖 く ノ 型 かた 煉 れん 獄 ごく , Ku no kata: Rengoku?, lit. Ninth Form: Purgatory) - The most powerful Flame Breathing technique. The user assumes a high stance before performing an extremely high-speed dash towards the target and unleashing a singular, devastating slash.
When it comes to pure strength, Shinobu Kocho is the weakest Hashira in Demon Slayer. She doesn't even have enough strength to decapitate a demon's head and she makes up for it by injecting poison into the demons.
Like many other aspects of the Demon Slayer Corps, the first Demon Slayer Mark was found on Yoriichi Tsugikuni, the inventor of Sun Breathing. He is the only known human to have been born with the Mark, a flame-like pattern on his forehead.
Demon Slayer has peculiar characters with incredible strength, skill, and presence. But, among this group of eccentric people, Kyojuro Rengoku still stands out from his colleagues due to his upright and exceptional bright personality. Yet, his fiery hair is also one of the biggest reasons he stands out.
Kyōjurō was 20 years old at the time of his death.
If he survived he would've continued to live a life dedicated to his mothers teachings. He would have also stayed on the Rengoku residence taking care of both his father and brother. I can also see him taking on Tanjiro as a tsugoku or apprentice to replace him as the new Hashira once he's retired in other words.
Shinjuro's stone-heartedness blinded him to the extent that even the death of his elder son Kyojuro didn't bother him. Moreover, he started berating his son and his capabilities in front of Tanjiro, and both of them got infuriated and fought each other.
The red Nichirin blade, wielded by Kyojuro Rengoku, symbolizes flame. The blazing Flame Hashira is charismatic and wonderfully eccentric. Kyojuro has a strong sense of morals, and his passion for demon slaying burns with the intense heat of a raging flame.
Despite coming from a long line of Flame Hashira, Senjuro never possessed any great skill in the art of Demon Slaying. As hard as he tried, Senjuro couldn't acquire the degree of swordsmanship needed to make his Nichirin Sword change color, and eventually gave up on following in his brother's footsteps.
Sound Hashira
He is the fastest Hashira, and the second physically strongest. Obviously, then, Tengen Uzui is rather proud. He is demanding, fussy, boastful, and prone to selfishness. But he is also ultimately kind and caring, with great love for his three wives as well as the other Hashira.
5/14 Fastest Hashira In Running
Despite his large and muscular build, Tengen Uzui is the fastest runner among the Hashira.
Senjuro tries to warn him that Shinjuro is a former Hashira, but, because he's being driven by so much anger and sorrow, Tanjiro continues to charge at him.
Shizuka is seen often teasing Sanemi and making him annoyed, nevertheless, the two had still created a strong bond and relationship with each other. Eventually, after knowing each other for a while, Shizuka finally ended up having the courage and confessed, leading to them getting married after awhile.
Ruka Rengoku ( 煉 れん 獄 ごく 瑠 る 火 か , Rengoku Ruka?) was the wife of Shinjuro Rengoku, and the mother of Kyojuro Rengoku and Senjuro Rengoku.
Giyu Tomioka and Sanemi Shinazugawa attend as the final surviving members of the Hashira, and together they they get a confirmation that not only are the demons all eradicated, but that the Demon Slayer Corps will be disbanding.
With that said, all Hashira in Demon Slayer have one glaring flaw: they're only human. As such, they're not infallible and are certainly not tougher than their demon enemies. This results in some rather lopsided matches and emotionally-charged oversights on their part.
He would be disoriented by the shockwaves created by Akaza's blows. Tengen has anti-demon bombs that can disorient them for a short period of time, but this wouldn't be an effective strategy when Akaza uses Compass Needle, which allows him to accurately pinpoint and aim for his opponent's weak spots.