Gengo Matsunaga, once known as Phoenix, was the greatest samurai fire-slayer in all of Edo. After leaving fire-slaying, Gengo is approached with an offer from the Shinjo Domain. Encouraged by his wife, Miyuki, he sets out to rebuild a fallen firefighting brigade. Gengo gathers a group of misfits, the Ragged Fire-Slayers, as they investigate mysterious fires started by the arsonist Kitsunebi.

The year is 1863, with the story being based in Kyoto. We follow a youth named Nio who is an honest and kind soul who's considerate of his family, yet he also has a hidden burning passion for seeking justice. From the time he came across Toshizou Hijikata and Souji Okita, members from a group of hated ronin known as the Miburo, his life then takes a turn to a bluer, and clearer path. Nio, alongside the other men whose hearts burn bravely and true, step forth towards an honest path with their blue wills adorned on their hearts!