Um, Actually

After discovering Nezuko's immunity to sunlight, Kagaya, the leader of the Demon Slayer Corps, declared a training regiment for all its members. A training regiment was devised for the lower-ranking Demon Slayers, where each part is supervised by each of the Hashira's, with the exception of Giyu who was initially unsure about his worthiness as a Hashira, and Shinobu who was tasked with aiding Tamayo with her research. We follow Tanjiro as he completes each of these trainings of the Hashiras, beginning with fitness and stamina training under the retired Sound Hashira. Other trainings includes flexibility training under the Love Hashira, swordsmanship training under the Serpent Hashira, and finally ending with the most gruesome training under the Stone Hashira.