Not long ago, Tanjiro and Nezuka, a boy with his demon sister, appeared in the Hashir Corps. Everyone was surprised and of course, Giyu Tomioka, the water hashira, stood up for these two. About a month passed and Tomioka suddenly disappeared after his usual patrol.

At one of the evening meetings, Tanjiro burst into the meeting room with news that shocked everyone.

Tanjiro: "Sorry! But, Giyuu-san is back! He-.. He's a demon!"

Giyu stood behind him, clearly not wanting to say anything yet. His hair had become longer and more voluminous, and his pupils were black. Instead of ears, he had "Siren ears", almost like those spoken of in mythology. There were blue marks on the face in the form of drops and waves.