It all began one day when Akira Fudo left to feed the rabbits. When he opened the cage door, he noticed that 2 rabbits has been slaughtered. Akira is shocked by the senseless massacre and goes in the take a closer look inside. He gets surprised that a third rabbit was under the litter jumped on him. Akira was thankful that at least one of the rabbits survived and wonderd who could have been so cruel. Next thing he knew, someone was behind him...

Miki is standing outside and wondered where Akira could be. A friend of hers notices her and informs her that she waits outside sometimes. She tells Miki that Akira was feeding the rabbits. Miki thanks her and that if she needs to see him, she knows where to look.

Akira is now being harassed by three gang members, teasing him about him and Miki. Akira tried to run, but his hand gets shot by a BB from one gang member's hand-held slingshot. One gang member took out a bike chain and ordered Akira to let the rabbit go so he can kill it. Akira begged them to leave it alone, but only gets kicked in the gut. They still order him to let go of the rabbit, but Akira still said no. The guy with the bike chain used his weapon at Akira and gave him a warning shot. They order him one last time to let go of the rabbit. Akira boldly says "No!" That was enough to get a bike chain struck on Akira's forehead, and blood starts to drip from his wound. Before the guy with the bike chain could strike again, one guy told him to stop. He said he would let the rabbit live, but tells Akira to "be smart or be killed".

The next thing they hear is that is Miki prying around and wondering why they're being so secretive. Then, she notices Akira on the ground and runs to him. The three gang members run off with Miki shouting at them as they run away. Miki asks Akira if he's ok, but Akira just sits there in embarrassment.

The next scene is where Akira & Miki are in the nurse's ward. Miki tells Akira to sit down, but he Akira says that he's fine. Miki then pointed to a mirror, and Akira decided to sit down. Miki then broke out a first aid kit and dressed Akira's wound and applies a Band-Aid. Now they leave school.

Akira & Miki is walking down a street, talking talking about stuff. Then, someone called for Akira from the shadows. It was Akira's old friend, Ryo Asuka. Ryo said that he needs to talk to Akira. Miki thought it was something other than an emergency, for she thought that Ryo looked "pretty". Akira asked Ryo if Miki could go with them. Ryo pulls out a knife and says that he doesn't want anyone else... just to see Akira. So Akira said good-bye to Miki and left with Ryo.

Inside the car, Ryo opened out to Akira and told him that his father committed suicide. He told him how that tragedy came to be. He said it started when he found his canary mutilated beyond recognition. Then, the next day, his dog John, was decapitated. Ryo came to his father about it, but his father said that the dog went crazy, and he had no choice but to kill it. (That would explain why his father's clothes were soaked in blood). He said he would get a new dog, one bigger, meaner and one worthy enough to kill. The straw the broke the camel's back one night when Ryo woke up and found his father with a knife in hand and planned to kill him while he slept. He woke up in time and pushed his father away. Then Ryo's father ran outside, doused himself in gasoline, and lit a single match.

Akira was surprised about this, but more shocking revelations was about to come. He said his father's charred body weighed twice as much as when he was alive. Ryo also mentioned that his father left him an inheritance... something he'd wish he had never laid eyes on. However, he does know that he must face it, for he couldn't keep this terrible secret to himself much longer.

The next phases to where Ryo and Akira are at Ryo's home. Ryo tells him that when his father was on an expedition in South America, he stumbled into a hole, slid down several hundred feet, and found an unusual item. They walked into a room and showed him this artifact. Akira ran away, but Ryo pointed out that it was artificial. Ryo mentioned that this item was shaped like mankind's image of the Devil. He told his friend that it came from a time when demons ruled the earth before the dinasaurs, and it was made by something that was not human. Ryo puts it over his head and tells him that anyone who wears it will see in his or her mind the demon world. He asked Akira to put it on so they could know why his father killed himself. Ryo was reluctant, but Ryo puts it on Akira. Akira could see in his mind what the demon world looked like.

The next scene is where Akira and Ryo describe what they have seen in the demon artifact, and the possibly of demons still in existence on Earth. Akira thought that mankind was lucky that demons died out before mankind was created, but Akira pointed out that how can mankind have known of demons if they did not exist in their time... like the legends of demons around the world. Ryo then tells Akira about Dante's "Divine Comedy" where Dante described Hell, Purgatory and Heaven. Ryo goes on and tells Akira of how Dante saw Lucifer, the bat-winged ruler of all demons trapped in ice, locked in motionless torture. Akira then thought that maybe Lucifer was trapped in ice during the Ice Age and that maybe Dante really did see this demon.

Ryo did tell Akira that they cannot get any help, and that only he and his friend can defeat all demons, for Ryo said that all humans would think they'd be crazy. Ryo said that while mankind is unaware of the demons' existance, demons would sneak from the shadows and kill all of mankind. Ryo did say that his father left behind a plan on how to kill off dall emons, but they were attacked by a demon that looked like calamari. They both run off and get attacked by a demon spider. The demon spider mysteriously runs off. Ryo then shoots the calamari demon in the face with his rifle and runs with Akira. Quickly, they both run to the car to get a better chance at escaping from the demons. Ryo runs over the calamari demon with the car.

As they sped off, Ryo gives Akira his rifle and tells him to be ready to shoot. Ryo stopped the car when he saw a hole in the road. Ryo stopped the car and a demon emerges from the back seat. Akira tries to open the door, but the demon fused the car door shut. yo then tells Akira to break the window and escape. Ryo takes the rifle, narrowly missing a shot of acid from the demon's mouth and shoots it point blank. Then a demon from the air swoops down and attacks them both Ryo shoots the demon's claw and then at its stomach. Ryo shoots the car twice so that the car would explode, killing both demons.

Ryo wipes some blood from his brow and apologizes to his friend Akira for mixing him into this mess. Ryo said to his friend that to him, everyone looked like an enemy except his friend. Akira understands, but while they were talking, one of the demons survived the explosion and grabbed Ryo by the ankles. Akira grasps the rifle and the demon tries to get a hold of it as well. Ryo tells Akira to shoot, but for a moment, Akira was reluctant to shoot. That feeling subsided when Akira rushed to the demon and shot at the surviving demon twice, killing it instantly.

Akira gets jumpy and readies the rifle, thinking that the demon would attack again. Ryo told Akira that the demon is dead, and that he has done well. So they ran to the mansion and talk about that was Ryo's father's plan on how to defeat the demons.

They both quietly enter the mansion, so that no demon, if any, knows where they are. Ryo activates a secret elevator, and they both go in narrowly escaping an attack from a spider demon. In the elevator that where Ryo told Akira of his father's plan.

Ryo's father's plan was that in order to defeat the demons, that you must become one with a demon yourself. It meant to no longer be human, not to feel love, happiness, sorrow...the essence of life itself! Ryo continues that it's possible that you can possess a demon instead of the demon possessing you by having a will that would overcome the demon's consciousness. However, if your will cannot overcome the demon's consciousness, it's best to choose death, like Ryo's father did. Akira thought it over and decided to go with Ryo's plan. Ryo opened a door where Ryo said it is the way to the River Styx.

The scene fades into a big party, full of loud music, booze and drugs. Akira talkrf to Ryo about this, and Ryo started to laugh. Akira thought it was some sort of weird jokem but Ryo explained that it's a celebration of the Sabbath, a holiday where it is one of the easiest days to get possessed. He also explains that demon rely on instinct, and that in order to be possessed they must cast aside all reason and act on instinct, for demons despise all reason.

Ryo also mentions that the other people would also be possessed and become demons. Akira said that to fight so much demons would be suicide. Ryo quickly explained that they must fight hundreds or thousands of demons and that if they cannot fight off this much demons, then there's no point in fighting at all. Ryo then mentions that he doubted that both he and Akira would survive together, so he says that whoever survives must save all of humanity from the demons.

The music and lights start again and one girls asks Akira to dance. They and all the others continue to dance and have fun, until some hear the screaming of a young woman. The crowd sees Ryo with a broken bottle in a young woman's shoulder and rants about how demons love blood and he continues to slash and kill other people with the broken bottle. Some of them get to Ryo and starts beating the crap out of him. Ryo falls to the ground and some guys kept kicking him. Akira runs toward the scene, but some guys kept pushing him pne by one until he lands on a woman's big breasts. She kicks his ass as well. Everyone starts laughing even as some feedback kicks in and the lights stop. All that stop until one girl feel the pains of the damned.

Slowly she turned into a demon, and one of her eyes bulge out. Her breasts melted away to reveal two faces with long, sinewy, red tongues. Her arms split in half. Then, other people slow turn into demons, until have the people in the room have become possessed. Ryo runs to Akira and asked him how he feels. Akira told his frind that the he felt nothing. They both failed and start to run away along with the other people who tried to run away. Akira runs to face one of the demons face to face. He screams and runs away again, that was until he felt something strange. He closes his eyes and raises his arms. He starts to chuckle and he opens his eyes. He turns his head and the Band-Aid that was on his forehead peels off and falls to the floor. He shouts that he is turning into a demon until he turns into one, and calls himself Devilman.

Devilman grasps one the demons by the head and squeezes until he kills it, symbolizing that he was created to eradicate all the demons of earth. Devilman continues to kill off the many demons in the room. Ryo look to see the carnage, and sees the demon that is killing off all of the other demons. Ryo sees that Akira, t he sweet, gentle, harmless friend that he knows so well, now enjoy slaughter and carnage. He thought that by creating mankind's savior, hemay have created mankind's greatest enemy.

The next scene fades to where Akira has turned back to normal and sees all the carnage that has been left in his demon form. Akira looks for Ryo and finds him on the floor, on top of a dead demon. He tries to wake him up and finds that it is too late. Ryo is dead and Akira is left alone to destroy all demons by himself.