Ichinomiya Kantarou grew up with the ability to see demons, but was isolated and bullied by others who did not share the same gift. Instead, he became being friends with the demons, gaining a great attachment to their existence. One day, Kantarou was told about the strongest demon, the one known as the ogre-eating Tengu. Amazed by the news of his strength, Kantarou vowed to find this demon who was far stronger than any other, deciding to call him Haruka when he did so. Since this time, Kantarou searched far and wide for the ogre-eating Tengu with no luck, making his living by becoming a folklore writer and demon-buster. On a particular job, Kantarou had finally found news of a nearby shrine supposedly the place where the ogre-eating Tengu was sealed.

At the pinnacle of his gymnastics career, Joutarou Aragaki—nicknamed Samurai for his signature hairstyle—suffers a shoulder injury following his wife's death. Five years later, he continues to push the limits of his body as a member of the Japanese gymnastics team. However, Joutarou's strenuous training fails to show any progress. His coach, Noriyuki Amakusa, advises that he retires. Together with his exuberant and supportive nine-year-old daughter, Rei, Joutarou takes a trip to Ego Wonderland to break the bitter news to her. However, their excursion ends in an odd encounter with a peculiar self-proclaimed ninja named Leonardo. He follows them home and interrupts Joutarou's every attempt at telling his daughter. Upon learning that Leonardo hopes to witness his gymnastics again, Joutarou astounds Japan with his announcement that he is not retiring. Joutarou dedicates himself to the biggest challenge of his career to prove that the gymnastics world is right where he belongs.

The United States of America has been in chaos ever since the emergence of D2s, an invasive species originating from a black meteorite that fell to Earth. A public decree banned citizens from playing any melodies, to prevent further casualties caused by the D2s' hatred for music—even now, in 2047, this prohibition is still in effect. Humanity's only form of defense against the D2s are Musicarts, young women representing pieces of classical music; and Conductors, the ones controlling them. Takt Asahina, an aloof piano prodigy, finds himself transformed into a Conductor following a spontaneous D2 attack. The same incident kills Anna Schneider's younger sister, Cosette, and brings Takt into contact with his Musicart, Destiny. Searching for a means of stabilizing the pact between themselves, Takt and Destiny—alongside Anna—embark on a perilous journey to the Symphonica Headquarters in New York City. Takt is in a hurry to reach the city so that he can play the piano again, even though his passion attracts the creatures he has come to despise. Meanwhile, Destiny's sense of duty drags the group into trouble along the way. With a D2-infested path and many more arduous obstacles ahead of them, will the trio make it to New York City in one piece?

The story is centered around a small group of guerilla freedom fighters on a colonial planet named Deployer, who are known as the Deployer 7, or Sun Fang team. In an unexpected coup, the elected Governor of Deployer becomes dictator and rules Deployer under martial law with the support of Earth's Federation. Fighting for independence from Earth's Federation influence, the freedom fighters begin a rebellion against the Federation's Combat Armors using a Combat Armor of their own: the Dougram. (Source: AniDB)