Demon Slayer: Kimetsu no Yaiba has introduced the strongest Breathing Style yet with the newest episode of the series! After a two year wait, Demon Slayer is finally adapting brand new material for the anime following the events of the Mugen Train feature film and the retelling of that arc over the first seven weeks of the second season. This means we finally get to see what came after Tanjiro got some clues about the Hinokami Kagura from Kyojuro Rengoku, and ended up getting the biggest clue yet with the reveal of a brand new breathing style fans had no idea about.
During the events of Mugen Train, Tanjiro had learned from Kyojuro Rengoku that while he had no idea what the Hinokami Kagura was (even as the Flame Hashira), there might be some clue about it within the old records of the former Hashira. The first episode of the Entertainment District arc confirms this to at least be the case as Kyojuro's father, Shinjuro Rengoku, revealed that there's actually another secret breathing style that seemingly has been lost to time, Sun Breathing, that he touts as the most powerful of all.
The first episode of the Entertainment District arc sees Tanjiro heading to the Rengoku household to pass on his final messages to his family. It's here that Shinjuro immediately accosts him, and claims that he know about Tanjiro's earrings from the book from the Flame Hashira records. He assumes Tanjiro is a wielder of the Sun Breathing technique, and reveals that this technique was not only the very first style ever created (which all of the other Breathing Styles branch off from), but it's also the most powerful of them all.
Shinjuro even goes as far to tease that all of the other styles are basic mimics of Sun Breathing, but Tanjiro can't piece it together. As far as he knows (and the records for his family show), he descends from a long line of humble coal workers. At the same time, he's still very curious about the Hinokami Kagura and this new Sun Breathing style is his biggest clue to finding out how to not only further strengthen this technique but perhaps even evolve it in a whole new way.
Unfortunately Shinjuro destroyed the book with Sun Breathing's details in it, but now Tanjiro has a path to follow and discover more about his own latent power. What do you think? Hoping to find out more about Sun Breathing as the season goes on? Let us know all of your thoughts about it in the comments! You can even reach out to me directly about all things animated and other cool stuff @Valdezology on Twitter!