Giovanni is a young boy who lives on the outskirts of a small rustic village. His mother is bedridden and his father has not returned home since leaving to work on a fishing boat. An outcast at school, Giovanni has only one friend: Campanella, the mayor's son. During the town's Festival of Stars, Giovanni starts to daydream atop a hill and looks up to find a steam engine train floating in the air. He boards the train only to find his friend Campanella already there. And so, the two begin their journey through the stars where they come across unusual people and visit many beautiful and haunting places.

When Demon Queen Echidna begins her invasion of the human realm, the people turn to the hero Leo Demonheart to protect them. Blessed with insurmountable power, Leo easily repels Echidna's army, thereby saving the world. But instead of gratitude or admiration, Leo is met with disdain and scorn from his fellow humans, who fear his overwhelming strength and believe that it may eventually cause humanity's demise. Banished from the kingdom he once called home, Leo wanders aimlessly throughout the land until, one day, he hears rumors of Echidna's efforts to rebuild her army. Hoping that demonkind might accept him as an ally, he returns to the demon queen's castle and offers Echidna his help. Naturally, Echidna immediately rejects him. Still, not all hope is lost, as Leo manages to convince Echidna's four generals to let him secretly work under their supervision. Donning the identity of a masked dark knight named Onyx, Leo solves the demon army's problems one by one—gradually improving the quality of life around the castle. Above all else, however, Leo wants to accomplish one goal: to learn why Echidna started the war in the first place.

Enma is a character created by the genius manga artist Go Nagai. Now, the popular character makes his appearance in an alluring Japanese horror anime for adults. It's a hair-raising erotic suspense in which Enma takes on complicated and gruesome incidents caused by demons who lurk in the darkness. But humans have lit up the darkness of the night with neon lights and turned their world into one that never sleeps, so demons now lurk in the "darkness of the human heart." Unfulfilled hearts, suppressed hearts, despair,...such darkness of the heart is the place they lurk. Enma is the Demon Prince of the Underworld, a demon "Born of Fire." His mission is to take back or destroy demons that have escaped to the human world from the Underworld. Along with his partner, Princess Yukihime, "Born of Ice," and the monster, Kapaeru, Enma sets up "Enma's Detective Agency." Tonight, like any other night, they will roam the sleepless city. Horrific incidents that could not possibly be human acts occur one after another. The stench of evil lingers at the scene... Enma's fire rips through the darkness!

Two years after the battle against Eosmon, Davis Motomiya, Ken Ichijouji, Yolei Inoue, Cody Hida, T.K. Takaishi, and Kari Kamiya meet a boy named Rui Owada, who is found with a depowered Digivice and claims to be the first Digidestined ever. In addition, a Digimon named Ukkomon appears in the real world, who wants every person in the world to have their own Digimon partner.