The plot of the series centers around three devils, Carrera, Mercedes and Rati, who are summoned to Earth to capture souls, which are then processed into brilliant gems.
As the story begins, a nerdy boy named Ogawa uses an ancient text in order to summon a devil to gain revenge against those who have mistreated him. When the devil turns out to be Carrera, however, he completely forgets the reason why he summoned her and instead has sex with her. He is unprepared for her hyperactive libido, though, and by the time morning comes he is too exhausted for the devil to take his soul. After this, the upper demons punish Carrera for failing to get Ogawa's soul. This leads to five days of imprisonment in which Mercedes and Rati satisfy themselves with Carrera.
Meanwhile, a group of angels have noticed a number of missing souls on Earth. Concerned that the laws of reincarnation are being violated, the angels concoct a plan to capture and "purify" the devils who are stealing the souls.
Meanwhile Ogawa misses Carrera and attempts to summon her, instead Mercedes answers the summons and Ogawa is very upset. Mercedes is also angry that Ogawa wants Carrera over herself. Ogawa takes out his frustrations by forcing Mercedes to have sex with him and she then returns to hell angry and embarrassed. Ogawa tries to summon Carrera again and succeeds. The angels, however, are prepared and manage to capture Carrera after Ogawa summons her. Ogawa then summons Rati, who flies off to heaven to rescue Carrera but is captured herself. Ogawa uses the summons a fourth time and gets Alphina, Ogawa begs Alphina to let him help rescue Carrera along with Mercedes. The climax is a battle in heaven between Carrera and Rati and their captors and Alphina, Ogawa, and Mercedes and the warrior angels. Later, we find out that the three devils have moved in with Ogawa and they will have multitude of sex. Alphina's fate is unknown.
It has been often stated to be a perverse version of Ah! My Goddess, as certain concepts are held in the same light.
Note: It is indicated several times in the show, that the souls are only used to create crystals. Once a crystal is made the soul is returned to its owner. It is not made clear why the demons need the crystals or why the angels don't notice the souls being returned.
Carrera: The main character; she is a blue-haired, buxom devil with a tremendous sexual appetite. She is also the top soul-getter of the three, primarily because she doesn't take her job too seriously. She also doesn't like the fact that Mercedes resents her for getting more souls... and of good quality, too. Carerra has big breasts, sexually attractive, a finely-tuned rear, a dirty mouth and is always sexually aroused. She also shows the least degree of embarrassment because of her sexual activities.
Mercedes: A red-haired devil, she is Carerra's closest friend/lover/rival. Unlike Carerra, she takes her job a little too seriously - mainly from her jealousy of Carerra's success, and as a result makes a lot of mistakes - like stumbling while carrying a full-course dinner or breaking plumbing with her bare hands while drawing the bath, which usually results in her returning to the underworld dejected and empty-handed. Otherwise, she likes to claim that her specialties range from bathroom cleaning to conquering the world. She shows a great deal of embarrassment from sexual activities, particularly in the scene where Ogawa forces her to have sex with him in a public park.
Voiced by: Lainey Thomas
Rati: A pink-haired devil who looks like a little girl but is definitely fully adult. Like Carerra, she is usually successful in capturing souls, and is often on the receiving end of Carerra's sexual attentions.
When Carerra failed to deliver Ogawa's soul, she was punished by being confined in a cell for five days. After Mercedes had seduced her, Rati had visited. Seeing Carerra bound up and nude, Rati then approached her and seduced Carerra herself... but with bad timing, because Carerra was set free soon after... and returned the favor to Rati. Rati is shown at one point wielding a type of mace in combat against heaven's guardians. She does not appear to be very adept as she is still captured.
Voiced by: Fran Scarns
Alphina: A blond-haired incubus (male counterpart to a succubus), Alphina is Carerra's, Mercedes' and Rati's boss. He usually stays behind in Hell to process the souls gathered into crystals, but can be summoned if no one else is there. He is also equipped with two functional penises. The angels refer to him as the "White Devil". He is the only devil shown to be adept in combat, wearing a battle suit similar to the warrior angels. He apparently had former..."relations" with a consenting angel. The nature of this relationship has yet to be clarified.
Ogawa: He is the one who summons all the devils, mostly because of Carerra. He had originally obtained the ancient book in order to gain revenge against those who had ridiculed him. However, upon seeing Carerra, all reason left him and he seduced her. Unfortunately, he was unprepared for her libido, and was exhausted when she finished (too exhausted for her to take his soul). After Carerra returned to Hell, Ogawa began to miss her after some time, and attempted to summon her once more. However, this was during her five-day confinement, so he summoned Mercedes instead.