Souma Kenichi is in a bit of a pickle. A group of thugs has cornered him on the side of the road and seem very intent on his life. Desperately fighting them off with the longsword he can summon at will, he is saved when a famous teacher of the Miyazaki School and his student intervene on Souma's behalf.

Confused but grateful, Souma learns that the sword he wields is called a "shinbuki", or true weapon. Stronger than any steel blade, a shinbuki is created by channeling inner energy into your surroundings and materializing it into a weapon.

Normally, learning to wield these supernatural weapons takes years of training under a master. However, a coveted few like Souma are born with the ability to wield shinbuki at birth, and master its use at a startling rate. These rare prodigies are called "Tensaiji".

Hunted by a mysterious organization intent on eliminating him before he can become a threat, Souma has little choice but to accept his benefactor's offer of free admission into the Miyazaki School.