Tengen Uzui, the flamboyant Sound Hashira of the Demon Slayer Corps, is an eccentric individual who tends to get flashy even while fighting. In his first encounter with the Upper Rank Six, Daki, he decapitated her in the blink of an eye, without her even noticing. He even trolled the demon by stating that she was not a good fit for the position of an Upper Rank.
The lossof his left arm in the battle didn’t stop him from overwhelming the other Upper Six, Gyutaro. At last he successfully, in conjunction with Tanjiro, decapitated the demon. What’s next for the Sound Hashira? Will he be able to continue his life as a Demon Slayer or will he step down from the position?
Tengen Uzui retires from the Demon Slayer Corps to fulfill HInatsuru's wish, but doesn't make a complete exit
During his battle with the Upper Demon Six, a flashback of him and his three wives was shown paying respects to the deceased Uzui siblings tombstone. After a while, Hinatsuru tossed her request upon Tengen. She asked him if they could withdraw from the frontlines after they defeat an Upper Moon Demon.
Tengen lost his arm and was seen lying on the ground unconsciously because of the effect of Gyutaro’s poison. Subsequently, he rejoined the battle by protecting Tanjiro with one blade in his right hand and the other clenched in his mouth. The loss of an arm didn’t stop Tengen from going all out and giving an enthralling fight.
The Serpent Pillar, Obanai Iguro appeared out of nowhere in front of Tengen, and mocked him in a careless demeanor for having taken so much time for eliminating the weakest Upper Rank Demon, and losing his left arm and an eye in the process. He even asked how long it would take him to recover from the injuries to get back on the frontlines.
Tengen simply said he couldn't fight anymore, was going to retire and hoped that the leader of the Demon Slayer Corps, Kagaya Ubuyashiki would forgive him for his decision.
So in a nutshell, Tengen Uzui is going to retire from the Demon Slayer Corps. With his disability, he won't be able to take on an Upper Six Demon in the long run. Moreover, the foremost reason for his retirement is to fulfill Hinatsuru's wish, because he holds a large amount of respect for his wives and deeply cares for them.
But hope is not lost, as he later becomes a teacher in the Demon Slayer Corps and becomes responsible for the basic level of training in endurance. He also oversees the performances of new recruits with his three wives. Tengen becomes a very strict individual when it comes to their lack of keeping up with his stamina training.
It is unlikely that the Tengen Uzui will ever rejoin as a Hashira. However, he has high hopes for Tanjiro, Inosuke, and Zenitsu, and believes that they will become the best version of themselves.