In 2121, the blue planet was hit by a meteorite containing mysterious power. Affected by this power, some creatures have the superhuman ability to fight with weapons derived from their own bodies. This type of creature is called "Bone Demon" by ordinary humans...
A seventeen-year-old boy came here unexpectedly from the distant past, but became the key to changing the world...
"Tch, it's not all your fault for being so mysterious." A certain boy squatted in the corner and muttered.
"Shut up." An arrogant and cold voice sounded from above his head.
Purpose: cherish the present moment