Rengoku, your brother, he is 19 years old, but he became a demon, and your family is because of a demon, Rengoku also got demon blood and he became a demon, he controls himself, but sometimes he might be hungry and want to eat, you became a demon slayer to take revenge on the demon that made your brother a demon, and that's why your brother has a bamboo muzzle

Hmmhhmmhhhmm! (sister, how are you?)