WARNING: The following contains spoilers for Demon Slayer: Kimetsu no Yaiba Season 2, Episode 1, "Flame Hashira Kyojuro Rengoku," now streaming on Funimation, Hulu, and Crunchyroll as well as Demon Slayer: Kimetsu no Yaiba the Movie: Mugen Train, now streaming on Funimation and Crunchyroll.
The Season 2 premiere of Demon Slayer puts Kyojuro Rengoku back in the spotlight. Unlike his appearance in the Demon Slayer: Mugen Train film, Rengoku doesn't have the misfortune of running into an Upper Rank this time around. Flexing on a mid-level Demon the way a Hashira should, Rengoku not only clowns the Demon known as Slasher but shows off a new power of Total Concentration Breathing, the signature ability used by the Demon Slayer Corps.
In Mugen Train, Rengoku instructs a wounded Tanjiro to use Total Concentration Breathing to staunch the bleeding of his stab wound. When Tanjiro succeeds, Rengoku informs him that mastery of TCB can allow a person to do all kinds of things. In Demon Slayer's Season 2 premiere, Rengoku shows off his mastery of Breathing by using it to run at inhuman speeds, covering miles of ground in mere seconds.
The Demon antagonist in this episode, Slasher, appears to possess a Blood Demon Art that allows him to move at near-supersonic speeds, turning him into a bright, blue blur. Despite Slasher's significant head start and traveling miles away, Rengoku is upon him almost instantly, covering the same amount of ground in a shorter amount of time by simply running. Most interestingly, Rengoku doesn't even appear to use a Flame-Breathing technique in his pursuit.
The majority of Rengoku's fighting in Mugen Train was done in a losing effort against Akaza, Upper-Rank Three of the Twelve Kizuki. Unfortunately, Rengoku's defeat failed to fully highlight the unbelievable strength of a Hashira of his caliber. Keeping in mind that Slasher can travel miles in an instant, Rengoku still has the audacity to call the Demon "slow" as he effortlessly beheads him. This anime-exclusive episode gives Demon Slayer's audience a better idea of what Rengoku can do in situations other than a fight for his life.
Total Concentration Breathing has been a staple of Demon Slayer from the start, but it's mostly been portrayed as a real-life stat boost. The Hashira of the Demon Slayer Corps are the ultimate masters of TCB, yet they haven't seen much action yet in the series. As a result, the technique's full power remains unknown. Seeing Rengoku use Total Concentration Breathing for something other than swordsmanship makes it clear that Tanjiro and the gang have not even scratched the surface of what it can truly do.
It's a bold move for the series to start its long-awaited second season by backtracking and even going as far as creating an anime-exclusive prequel episode centered around a soon-to-be-dead character. Using the premiere to expand on not just Rengoku's character, but the fundamentals of Total Concentration Breathing is a great move to help keep things feeling as fresh as they can be during a recap arc. When Season 2 inevitably moves past Mugen Train and onto a new Hashira, it will be exciting to see what else the audience might learn about the world of Demon Slayer.