That is the reason why during a Hashira meeting that his father didn't attend, Kyojuro decided to talk to Ubuyashiki and the other Hashira and ask to be appointed as the new Flame Hashira, replacing his father who is currently incapable of fulfilling his duty.
Following his demise at the hands of Akaza, Flame Hashira's position fell empty. The only person who could fill the position and carry on the family tradition was Kyojuro's younger brother, Senjuro Rengoku.
Specifically, Kyojuro was the Flame Hashira who made use of the Flame Breathing. While not having his life being directly affected by Demons like many other members in the Corps, Kyojuro household had produced Demon hunters for generations.
With Last season's Mugen Train Arc and Entertainment District Arc brought Rengoku, the flame hashira, and Tengen Uzui, the sound hashira. Now, with Demon Slayer Season 3's Swordsmith Village, two more Hashira have come into focus: Mitsuri Kanroji (the love hashira) and Muichiro Tokito (the mist hashira).
It's noted that, at some point in his life, Senjuro was to become Kyojuro's successor and so had been training to become a Demon Slayer.
In the Demon Slayer Corps, the Hashira is a group of the strongest and most reputable swordsmen who have defeated members of the Twelve Kizuki. Yet, for some reason, Tanjiro Kamado, the series' protagonist, never becomes a Hashira.
Who is Rengoku girlfriend? Mitsuri Kanroji. The two of them share a gluttonous side and enjoyed snacking on their breaks. Mitsuri derived her own unique Breathing Style, Love Breathing, from his Flame Breathing.
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.
Mitsuri Kanroji is an emotional and passionate girl who compliments people in her head constantly, most likely a contributing factor towards her nickname "The Hashira of Love", although she is rather shy and is easily flustered.
Jigoro Kuwajima (桑島 慈悟郎, Kuwajima Jigorō) is a supporting protagonist of the popular manga and anime series, Demon Slayer: Kimetsu No Yaiba. He is a former member of the Demon Slayer Corps, the previous Thunder Hashira and the former mentor of Zenitsu Agatsuma and Kaigaku.
Kyojuro Rengoku (The Flame Hashira)
At only the age of 20, Kyojuro surpassed his father, Shinjuro (a former Hashira), by taking down one of Muzan's subjects, Enmu, with a single mighty strike.
Tomioka Giyu = killed by Tanjiro Kamado. Tanjiro Kamado = killed by Nezuko kamado ( or another demon ) ; or executed for killing a hashira and have protected a demon. Nezuko Kamado = burned to sunlight , killed by a hashira , or eaten by Muzan Kibutsuji ( if she conquires the sun )
He partly blamed himself for not being strong enough, with his flame breathing style being distinctly inferior to the ultimate demon slayer art of sun breathing. Unable to master sun breathing and resenting its very existence, Shinjuro quit the demon slayer corps and retreated inward.
Due to his dominant Breathing Technique, he is considered to be an exceptional swordsman in his days of being a Hashira. However, one fated day after the death of his beloved wife, Ruka Rengoku, Shinjuro detached himself from the world he knew, forsaking the vow he took as a demon slayer.
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.
Tengen Uzui
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.
Gyomei Himejima, the Stone Hashira, is the strongest Hashira in the Demon Slayer corps in terms of strength and swordsmanship. He is the only person who uses spiked flails and an axe instead of standard swords to kill demons. Such a weapon takes immense precision and soundness to use without inflicting personal damage.
Sensing their despair, Doma offered a chance to him and turned both Gyutaro and Daki into demons.
Tanjiro's Current Demon Slayer Rank Is Kanoe
Not many of the Demon Slayers' ranks are known as of Season 2, but there are a few. Tanjiro, Zenitsu, and Inosuke have moved from Mizunoto up to Kanoe due to their exploits. Murata, the Demon Slayer, who was almost digested on Mount Nagumo, is also a Kanoe.
Some time after giving birth to Senjuro, she developed an untreatable disease and was left bedridden up until her death. Right after Akaza says to Kyojuro that he's one of the strong and chosen ones, he flashbacks in his past memories and Ruka appears with a young Kyojuro.
Shinjuro Rengoku ( 煉 れん 獄 ごく 槇 しん 寿 じゅ 郎 ろう , Rengoku Shinjurō?) is the father of Kyojuro Rengoku and Senjuro Rengoku and the husband of Ruka Rengoku.
In Chapter 205, we see Obanai and Mitsuri reincarnated and married, as they promised before they died, and they are running a restaurant together. In the volume extras it is revealed that they have five kids.