Demon Slayer- Kimetsu No Yaiba Hashira Training... ((exclusive))

The arc begins following the revelation of Nezuko Kamado’s immunity to sunlight, a development that makes her Muzan's primary target. Recognizing the imminent threat, Kagaya Ubuyashiki initiates a rigorous training program led by the Hashira —the most elite combatants in the Corps—to elevate the skills of every member and help them manifest the powerful "Demon Slayer Mark".

Led by the retired Sound Hashira, Tengen Uzui . Demon Slayer- Kimetsu no Yaiba Hashira Training...

There are seven Hashira in the Demon Slayer Corps, each specializing in a specific area: The arc begins following the revelation of Nezuko