Nouvelle Tokio City locates on the place where it used to be Tokyo Bay. At the first glance, the prosperous city seems to enjoy its freedom and peace, but the city is suffering from the crimes. Senpuuji Maito is a perfect 15-year-old boy, bright, handsome, smart, and all-around sportsman. Furthermore, he is the leader of Senpuuji Trading group, and a multimillionaire. He spends his private fortune to found Brave Express Squad? which consists of several robots. They are the robots that have various special abilities. Above all, the leader, Gaine, has a super artificial intelligence and has own personality. They can transform into trains. In case of incidents, they will appear anywhere in the world using the highly developed railway system.

Grade schooler Yuuta Tomonaga stumbles upon Deckerd, a humanoid robot under construction by the Japanese police, built to fight advanced forms of crime. Yuuta's constant contact with Deckerd gives the robot a heart, or personality; when Yuuta is recruited as the boss of the Brave Police as a result, a true human/robot partnership occurs. (Source: Wikipedia)

Dreaming of becoming a hero and vanquishing the Demon King, Raul Chaser enters the Hero Training Program in pursuit of his ambition. However, when the Demon King is defeated and peace returns to the world, the Hero Training Program is suspended indefinitely, making it impossible for anyone to become a hero. Two years later, Raul reluctantly works at a small electronics store called Magic Shop Leon. Though the former hero-in-training is plagued by the mundanity of working in retail, everything changes with the arrival of a new hire. Appearing at first to be just a boy with good looks, he turns out to be a female demon by the name of Fino Bloodstone. She is not just any old demon either—Raul's new coworker is in fact the daughter of the late Demon King! Handed the responsibility of training this eccentric new employee, Raul soon finds his life becoming livelier than it ever was before.

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.