If you're looking for manga similar to Dokkaebi Gamtu, you might like these titles.
Tachibana Riku is an orphan who lives with his adoptive grandfather. Other than school and homework, Riku has to put up with lessons from his grandfather, teaching him seemingly meaningless hand signals and signs; meaningless, that is, until Riku is violently introduced to the world of 'shikigamis', fighting beasts with human owners. After witnessing his grandfather defend against a shikigami assault on their home shrine, Riku obtains his own Drive device to summon his own shikigami, Kogenta, and it turns out the hand signals give the shikigamis special powers. With his newly obtained powers, and a shikigami as a companion and friend, what adventures await Tachibana Riku? Do his powers have any relation to his parents' disappearance?
Beat has always dreamed of being the Golden Hero of Totia. He made a pact with his best friend Ricercare (Rice for short) to join forces to annihilate the demon king in order to achieve this aim. Yet a twist of fate causes him to abandon his goals and fight alongside Rice to protect the demons. Just how will they fare against the entire nation of Totia? And can Beat protect Rice from the hero of Totia before it's too late?
Frederica, the older sister. She contracts a demon, hunts the souls of the wicked, and sends them to hell. She is the silver seal. Howly, the younger brother. He was given his life by a demon, according to his sister's wish. He serves and protects the silver seal. He is the warrior seal. What will the world give to them?
Born into an aristocratic family of a large country, a boy with insufficient magic power bade farewell to his unlucky daily life. Because of his encounter with a Demon, his fate began to change. This destined meeting changed the boy’s life, affected his surroundings, and soon after, shook the entire world.