WARNING: The following contains spoilers for Demon Slayer: Kimetsu no Yaiba Season 2, Episode 8, "Sound Hashira Tengen Uzui," now streaming on Funimation, Hulu, and Crunchyroll.
Some people are just impossible to please, as evidenced by Muzan Kibutsuji's violent dressing down of Akaza in the first episode of Demon Slayer: Kimetsu no Yaiba's Entertainment District Arc. Reporting his failure to find the mysterious Blue Spider Lily as well as his successful elimination of a Hashira, Akaza is berated and summarily dismissed by his liege, angering the Upper-Rank demon. Yet Akaza's anger is not directed at Muzan or even himself, but rather at Tanjiro Kamado, who is apparently every demon's least favorite demon slayer.
If only Muzan were as blown away by Akaza's power as the fans were during Upper-Rank Three's debut in Mugen Train, but alas, the progenitor of demons is definitely not impressed. With omniscient knowledge of all his demons, Muzan knows full well that Akaza barely escaped the Mugen Train with his life, leaving three weak demon slayers alive and even having the utter distaste to be wounded by one of them. Akaza made a mistake in proudly declaring the death of a Hashira, because to Muzan, a demon killing a human is not an accomplishment, but the natural order of things.
After being violently and vehemently informed he has disappointed his master, Akaza is unceremoniously dismissed. In a rage, he destroys the sword Tanjiro had skewered him with. Recalling how the Demon Slayer protagonist called him a coward, the Upper-Rank demon places Tanjiro at the top of his hit list, vowing to splatter his brain matter all over the place the next time they meet. Considering that Muzan has put out a kill order on Tanjiro anyway, Akaza can kill two birds with one Kamado.
Despite being pulled apart like wet toilet paper by Muzan, Akaza's power is still fearsome. Objectively speaking, he didn't have to try that hard to kill Kyojuro Rengoku, spending most of the fight trying to convert the Flame Hashira to demonism. Even with months of training since this incident, Tanjiro is surely still nowhere near as powerful as Rengoku was, meaning if he bumps into Akaza anytime soon, he won't stand the slightest chance.
Tanjiro has recently learned that the Hinokami Kagura is actually a Sun-Breathing Technique, the most powerful Breathing Style there is. However, he'll have to master it in a hurry to avoid being turned into a red paste the next time he sees Akaza. After all, Rengoku only lasted as long as he did because Akaza was not actively trying to kill him for most of the fight -- an advantage Tanjiro surely will not have given Akaza's vengeful state of mind.
More so than usual in Demon Slayer, the clock is ticking for Tanjiro, having managed to piss off the fourth most powerful demon in existence. Getting stronger day by day by and continuing to master Total Concentration Breathing: Constant likely won’t be enough to save Tanjiro from Akaza's wrath. While it doesn't seem likely that Akaza will appear during the rest of the Entertainment District Arc, it didn't seem likely he would show up during Mugen Train either.