Hida Kizuna possesses the HHG (Heart Hybrid Gear) ability, but it is not strong enough to make him particularly important. His older sister calls him to transfer to a strategic defense school, where many of the students (many of which are large-breasted girls) use their HHG abilities to fight invaders from another world while wearing extremely skimpy pilot outfits. Kizuna's fighting ability doesn't measure up, but his sister has another plan—apparently having erotic experiences with Kizuna will allow the girls to replenish their energy or power-up. It looks like his new school life is going to be full of embarrassment.

Eighth-grader Shigeo "Mob" Kageyama has tapped into his inner wellspring of psychic prowess at a young age. But the power quickly proves to be a liability when he realizes the potential danger in his skills. Choosing to suppress his power, Mob's only present use for his ability is to impress his longtime crush, Tsubomi, who soon grows bored of the same tricks.

In order to effectuate control on his skills, Mob enlists himself under the wing of Arataka Reigen, a con artist claiming to be a psychic, who exploits Mob's powers for pocket change. Now, exorcising evil spirits on command has become a part of Mob's daily, monotonous life. However, the psychic energy he exerts is barely the tip of the iceberg; if his vast potential and unrestrained emotions run berserk, a cataclysmic event that would render him completely unrecognizable will be triggered. The progression toward Mob's explosion is rising and attempting to stop it is futile.