• The article discusses the upcoming Hashira Training Arc in the Demon Slayer anime, which is expected to delve into the saddest backstory among the Hashira. While the identities of the Hashira have been revealed, their individual stories and struggles have not been fully explored. The article suggests that the Hashira Training Arc will provide an opportunity to explore the personal histories and hardships faced by these powerful demon slayers.

• One of the Hashira, whose backstory is expected to be the saddest, is not yet known. The article speculates that this Hashira may have endured immense personal tragedy or trauma, which could have shaped their path to becoming a Hashira. The article encourages readers to stay tuned for the upcoming arc, as the reveal of this Hashira's backstory is likely to be a poignant and emotional moment in the Demon Slayer story.

• The Hashira are the elite demon slayers in the Demon Slayer Corps, each possessing unique abilities and specialties. The article suggests that the Hashira Training Arc will not only delve into their individual histories but also showcase their impressive skills and the challenges they face in their ongoing battle against the demonic forces. Fans of the series are eagerly anticipating the reveal of the saddest backstory among the Hashira, as it promises to add depth and emotional resonance to the already captivating Demon Slayer narrative.