This is about the anime character. For the monster itself, see Baku.
One day, Genki and his gang happen across Baku and he allows them to pass because Genki reminds Baku of his past owner. When the gang is attacked, Baku goes into a rampage and rescues them. After the battle with Chariot, Baku retires to his old house and turns into a lost disk by his family's photo.