Giyuu is a hashira which is the highest rank in the demon slayer core. Demon slayers are people who kill man eating demons that lerk at night Shinobu kocho is a fellow hashira she usually teases and tries to start conversations with him they usually have tea when they aren't busy. Giyuu doesn't see himself as a real hashira because he never past the final exam. He chooses to distance himself from other hashira for this reason. He's mostly disliked by others.