Shinjuro Rengoku

Shinjuro is a very short-tempered man, especially when regarding the Demon Slayer Corps and his son, Kyojuro, with the mention of either causing him to grow furious. He appears to be abusive, harshly insulting the recently deceased Kyojuro and knocking Senjuro to the ground during his fight with Tanjiro. He is also an alcoholic - his first action upon awaking after being knocked out by Tanjiro is to buy alcohol, and he is often seen drinking with sake. Shinjuro possesses feelings of inferiority, which stemmed from reading the chronicles of the past Flame Hashira, where Sun Breathing is described as the original and most powerful breathing style. He mocked the other styles as "cheap imitations" of Sun Breathing and accused Tanjiro of coming to their residence to mock them for his superiority.

After his wife's passing, Shinjuro began drinking while doing duties as a Hashira and eventually encountered Hairo who he, in a drunken rage, proceeded to cut various parts of his body without ever cutting his head whilst lamenting on why his wife had to die yet Hairo, a demon, managed to survive and that he sees that all the things he's done as utterly pointless and proceeded to tell Hairo that he was a coward despite being a demon and questions him if he really wants to keep escaping like a coward until he dies. Before retiring as the Flame Hashira, Shinjuro tore apart the Generational Flame Hashira Record of the Rengoku family.Overall Abilities: Due to his status as the former Flame Hashira of the Demon Slayer Corps, it can be assumed that Shinjuro is a very powerful swordsman. In a brief skirmish, he was able to completely overwhelm Tanjiro Kamado, a talented Demon Slayer who was pivotal in the defeat of Lower Rank 1 , Enmu, in hand-to-hand combat. He was noted by Tanjiro to not "move like an average person", hinting to his above average physical abilities as a seasoned Demon Slayer. A further testament to Shinjuro's strength is that he was able to defeat the future Lower Rank Two, Hairo, while in a drunken rage. Flame Breathing (炎ほのおの呼こ吸きゅう Honō no kokyū?): One of the core Breathing Styles, this style ran in the Rengoku family since the invention of Breathing Styles and is eventually passed down to his son, Kyojuro.

Shinjuro strongly resembles his sons, Kyojuro Rengoku and Senjuro Rengoku, possessing unruly orange hair that flares out around his face, becoming redder near the ends above his ears, that he wears messily tied back behind his head. He has fair skin, bushy black eyebrows and bright, orange eyes that redden near the pupils, that are slanted inwards and shaped so as to give him a furious appearance. Shinjuro wears a traditional kimono robe. When he was the Flame Hashira, he also wore the haori with flame-like ridges at the end that Kyojuro wore when he was the Flame Hashira. In the Infinity Castle Arc, he is shown with a katana with a flame guard similar to Kyojuro's, with what appears to be a flame pattern on the sheath.