Kyojuro Rengoku's Story: Part 1

This side story opens before Kyojuro Rengoku has earned the Flame Hashira rank. His father, the previous Flame Hashira, has fallen into drink and abandoned his duties, so the young Kinoe-ranked slayer steps forward to fill the gap. Doubted by the senior Hashira, he accepts a mission into Japan's capital to track a hard-to-find member of the Twelve Kizuki, hoping to demonstrate that he can carry his family's mantle.

A father's refusal

While training with his pupil and partner Mitsuri Kanroji, and sharing food prepared by his brother Senjuro, Kyojuro learns the Flame Hashira is summoned to a meeting. His father Shinjuro dismisses the order, hurls a flask at him, and belittles Flame Breathing as feeble, telling his son he will never become a Hashira.

The Hashira meeting

Kyojuro appears at the gathering in his father's place. Kagaya Ubuyashiki greets the corps while Sanemi Shinazugawa challenges the outsider's right to be present. To test him, Sanemi attacks; Kyojuro refuses to strike back, explaining that swordsmen should not turn blades on one another, which surprises the Wind Hashira. Kagaya then sends Kyojuro to investigate a suspected Twelve Kizuki in Tokyo, since the region falls under Shinjuro's jurisdiction.

Clash with Lower Two

In the city, a demon revealed as Lower Rank Two ambushes Kyojuro and Mitsuri with rifles, dynamite, and a shadow-based Blood Demon Art that summons firearms. The demon nurses an obsessive grudge against the name Rengoku yet fails to recognize Kyojuro at all. After protecting Mitsuri with several Flame Breathing forms, Kyojuro proudly declares his name and vows to slay the demon and become the new Flame Hashira.

The chapter is the opening half of a two-part gaiden collected in the Stories of Water and Flame volume, running in Weekly Shonen Jump in October 2020. It expands the backstory of both Kyojuro and Mitsuri, showing the early bond between teacher and student, and introduces the gun-wielding demon Hairo well before his identity is fully disclosed. Recalling his mother's words about keeping a fire in his heart anchors Kyojuro's resolve throughout.