Demon Slayer: I Am the Eldest Son of the Butterfly Family

[Transmigration] + [Fanfiction] + [Making things right] + [No angst] + [One heroine] + [No breaking up established couples] I transmigrated as a baby, but why am I by a river?! A new account! Don't mess with me!! No way. Am I, a transmigrator of all people, going to spend my short life in these desolate mountains? No way, I can still make it!! Butterfly Abyss wailed at the top of his lungs, and sure enough, someone found him and took him home. But a voice in his mind told him this was the world of Demon Slayer, where demons existed. Butterfly Abyss calmly said, “I don't care if you're a System or the mother of Blue Star. Please, save this child! Surely you don't want me to have a hard life out here...” The voice in his mind went silent for a moment, then left three glowing orbs in his mind. Heh heh heh~ Kibutsuji Muzan, who was posing as a human out in the world, inexplicably broke into a cold sweat. Was that sweat? No, wait!