Naoto-kun is in love with his classmate Rika Manabi. He gathers his courage and confesses to her - receiving a reassuring response - just about to rejoice in his good fortune, when suddenly the happy couple are attacked by a teenager calling himself Azuma, the Shogun of the Underworld. A mysterious sort of tentacles kidnap Rika, and if it were not for the angel's intervention Nao-kun would not have her purity. But an angel can't keep watch over Rika forever. Therefore, she must learn to fight back the devil's attacks herself. And the way to the cherished "hanshin" is through bed: only by gaining "love points", mastering all the techniques and tricks, Rika can become an angel of practical love!