WARNING: The following contains spoilers for Demon Slayer: Kimetsu no Yaiba Season 2, Episode 16, "Defeating an Upper Rank Demon," now streaming on Funimation, Hulu and Crunchyroll.
The ninth episode of Demon Slayer: Kimetsu no Yaiba's "Entertainment District" arc opened on a somber flashback to Tengen Uzui and his wives paying their respects to the Uzui family grave. The Sound Hashira has always been the flashiest man in the Demon Slayer Corps, but his eccentric behavior is more manufactured than he would have people believe. The self-proclaimed God of Festivals who demands worship and praise from his subordinates is actually just a wounded man doing his best to cope with his traumatic past.
Tengen Uzui was raised as a shinobi alongside his eight siblings by their obsessive, cruel father. When detailing his past to Gyutaro to get Upper Six to stop gushing over him, Tengen revealed that seven of his siblings died because of their father's shinobi training. Interestingly, the anime omitted a detail from the manga that adds another layer of tragedy to Tengen's childhood. During his conversation with Gyutaro in the manga, Tengen admitted that his father made the Uzui children fight to the death while blindfolded and unaware they were fighting each other, resulting in Tengen being responsible for the deaths of two of his own siblings.
In the anime, Tengen says only that his siblings all died as a result of the shinobi training. If the omitted detail from the manga is still canon, it would provide more insight as to why Tengen deemed himself doomed to go to Hell. Either way, Tengen deeply mourns his deceased siblings as he poured sake over the Uzui family tombstone and wondered if the Uzui siblings could have all gone out for drinks together someday had they all lived. Showing intelligence no doubt gained from his time as a husband, he quickly put an end to any self-pitying talk before his wives could scold him for it.
As Tengen, Hinatsuru, Makio and Suma shared a meal by the Uzui family headstone, Tengen vowed to his deceased siblings that he will continue living his life to the flashiest for their sake. Tengen admitted that he thinks of his siblings every day, and even though he misses them, he mainly mourns for the lives they never got to live. When Tengen rejected his family's ideology and fled the clan with his wives, he did so with tremendous guilt that he had gotten a chance at a life he actually wanted to live, unlike most of his siblings.
The idea that Tengen believes he is destined to go to Hell might also play a part in why he lives life as flashy as he can. As a Hashira in the Demon Slayer Corps, and as demonstrated by the events of "Defeating an Upper Rank Demon," Tengen's life could end at any moment, so he needs to do all the living he can, while he can. Tengen Uzui is the personification of the phrase "here for a good time, not a long time." Hopefully, the Sound Hashira's good time isn't over yet -- but, given that he was last seen missing a hand, unconscious and with poison spreading through his body, the signs don't bode well.
In a second flashback, Hinatsuru expressed a desire for a normal life with Tengen, Makio and Suma. Tengen's wives are trained shinobi as well, and Hinatsuru indicated that they've all taken lives as part of their shinobi training. Tengen and his wives fight demons to help balance the scales of their sins, and Hinatsuru believes defeating an Upper-Rank demon would be enough to allow the makeshift family to settle into domestic life with a clear conscience.
