"Promise you'll marry me?" (sanegiyuu)

Sanemi and Giyuu have known each other since childhood. They were inseparable, making promises to each other all the time, specifically a promise to marry each other. Until one day, giyuu's sister is killed by a demon, and sanemi, his best friend, is claimed dead after the people from the village think he's been murdered along with the rest of his family. A few years go by, and Giyuu is now a hashira, as he meets the other hashiras, he couldn't help but notice a certain someone that looks exactly like his childhood friend..