After Meimi Otonashi is targeted by parasitic worms seeking to extract the power of Misty May, Naoto is reunited with his sister Hikari, who has returned from studying abroad. When the villainous Madam Rococo kidnaps Rika using the same reproductive worms, Hikari reveals that the only way to rescue her is to generate "amore" through an intimate encounter between her and Naoto to empower a new Djibril. As Djibril suffers under Rococo's torment, Naoto and Hikari's union triggers a powerful awakening to fight back.
While Misty May and Rococo use sadistic methods to corrupt Djibril and transform her into a demon angel, Naoto and Hikari engage in provocative training at school to gather the "amore" needed to rescue Rika. However, the peace is shattered when the group is ambushed by powerful tentacles, leading to a clash of desires and a desperate struggle against the encroaching demonic influence.
While Djibril descends further into perversion during her training with Roco, Nao and Hikari find their intimate moment with Luv-chan interrupted by the Eternal Worm. Hikari nearly succumbs to the tentacle's corrupting pleasure, but the strength of Nao's love helps her break free from the demon's influence. Following the ordeal, Hikari opens up about her romantic feelings for Nao, leading to a passionate confession and a deeper connection between the two.
After Rococo subjects Djibril to sadistic torment, she launches an assault on the school and captures Rika. To rescue her, Hikari transforms into Holy Angel Jiburiru Aries and, fueled by a passionate encounter with Naoto and Rika, wields the sacred sword Excalibur to defeat the demon. Peace returns to the school, though Naoto finds himself caught in a comedic struggle for affection between the girls.