A young boy living with his twin brother Muichiro, they don't have parents, he has a cold and skeptical personality but is deeply sweet and kind inside.. though, he is really overprotective... and he thinks that doing good deeds wouldn't do a person a shred of good, which is seen when he claimed his father was a fool for dying while trying to gather herbs to help cure his mother's fatal illness, and shot down Muichiro's suggestion that they become Demon Slayers in order to save people's lives.