Rengoku become a Pillar (around age 18 or 19, and since he was raised practicing Flame Breathing he probably finished the Final Selection around age 12 or 13, so it clearly took him a more normal period of time to become a Pillar.
I would personally put Uzui below Tomioka and Renton because they all have been serving for a relatively similar amount of time but since Rengoku was around 15/16 yrs when he became a Hashira he would most likely be more respected than Uzui, who became a Hashira around 17/18 yrs when he became a Hashira.
9) Kyojuro Rengoku (20)
The Flame Hashira died at the age of 20, following an intense battle with Akaza. Despite having many severe injuries, Rengoku ultimately accomplishes his goal of protecting the Mugen Train passengers and his Demon Slayer juniors.
Kyōjurō Rengoku was 20 years old at the time of his death. He was the big brother everyone wanted and needed, the sacrifice and the impacts he made in the lives of Tanjiro, Inosuke, and Zenitsu in such a short space of time will forever be remembered.
1 Gyomei Himejima - The Stone Hashira
The oldest of the bunch, the Stone Hashira, Gyomei Himejima is 27 years old.
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.
Muichiro is a 14-year-old boy at the time of his death and had a youthful appearance befitting said demographic. His pale turquoise eyes are large and empty-looking and his complexion is very light. He is fairly short and had a delicate figure which led Tanjiro to believe he is physically weak.
Shinobu Kocho is a capable Demon Slayer whose worthy of being the Insect Hashira. That being said, she's arguably the weakest Hashira when it comes to pure strength.
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.
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.
Senjuro Rengoku | CHARACTER | Demon Slayer: Kimetsu No Yaiba Entertainment District Arc Anime Official USA Website. Kyojuro Rengoku's younger brother. He has a gentle, modest personality.
Full name: Kyojuro Rengoku. Age: 20.
The first Hashira to retire from this was Jigoro Kuwajima, Zentisu's master and the former Thunder Hashira. While Tengen proved he could technically fight with one hand and eye, he opted to retire instead. Even though he retired, Tengen oversees the stamina portion of the Hashira Training along with his wives.
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 )
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.
But there is one who is the friendliest of them all, and that is Kiyogiro Rangoku, the Flame Hashira. Among the pillars, there is not a single negative thing revolving Rangoku. Such an honest guy, and his character influences others positively. In Demon Slayer, Liu and Rangoku are not shown to have any interactions.
The Wind Hashira has one of the saddest backstories in Demon Slayer. His mother had turned into a demon and had killed five of his siblings. He was forced to kill his own mother in an attempt to save his only remaining brother, Genya.
Gyomei Himejima
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.
5) Rengoku (20 years)
Flame Hashira Rengoku always motivates those around him to become a better version of themselves. He is killed in the Mugen Train arc while fighting against Akaza. It is one of the saddest deaths in the series, but he manages to carry out his duties until his last breath.
Muichiro Tokito's character received an immense amount of growth in the Swordsmith Village. As the youngest hashira, Tokito is still discovering himself as a person unlike his sword-skill.
Haruka Shiraishi: Muzan's Daughter.
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.
Akaza is a stubborn demon who respects the strong and despises the weak. So much so, that the demon goes out of his way to challenge powerful fighters and demon slayers. In the Infinity Train Arc, he quickly took a liking to Rengoku, begging him to become a demon, so the two could continue dueling forever.
After the final battle
At the end of the chapter, there is a picture of Inosuke giving acorns to Aoi while she smiles. It is confirmed in the Volume 23 extras that Inosuke and Aoi did eventually end up together and that they have two great-grandsons, one of which is Aoba.