Based on the game by Front Wing.
When the summer break began, Jinno Naoto and Manabe Rika confessed their thought they had since their childhood and began to go out with each other. Suddenly a boy named Asmodeus appeared. He said he was a devil, and he tried to take Rika away. Naoto did his best to save Rika from Asmodeus, but he couldn't anything to do with devil's power. At that very moment, a girl Luvriel, who name herself an angel, came and saved them.
They took Luvriel injured in the battle against the devil. There, Luvriel told them the surprising things; angles in Heaven and devils in Hell have been fighting for a long time, and the devil would attack them again.
Because Luvriel had lost her power during the fight, she asked Rika fight for her.
On the other hand, the devil had lost his power in the fight. Then, Otonashi Meimi, who was a classmate of Naoto, happened to come and see Naoto confess his love to Rika, and she became jealous. Taking advantage of her jealous, he haunted her. He made Meimi into an evil heroine, Misty, and made her attack Rika again. On the other hand, Luvriel turned Rika into Sei Tenshi Djibril and let her fight against them.