Blue Exorcist is about a slightly disreputable but otherwise well-meaning boy named Rin Okumura who discovers that he is the son of Satan. (As a result, even when he tries to do good deeds something bad happens–usually to him, but also to anyone else in the general vicinity.) He and his much more responsible and respectable twin brother Yukio were both raised by a priest, an exorcist named Shiro Fujimoto. There is some random Kabbalah involved with the series, in that the human world is referred to as “Assiah.” (In Kabbalah Assiah is one of four spiritual “worlds”) The world of demons is referred to as “Gehenna.”
We open with some sort of dire ritual taking place. Some force appears to be trying to stop the ritual from taking place but a priest urges the monks to keep chanting. Then a few of the monks burst into blue flame which causes something of a panic amongst the monks. Then the priest leading the ritual explodes and the entire building bursts into flames and everything goes white, and our next sight is a boy getting punched in the face.
The other boys run away screaming “demon,” much to the disgust of the boy who threw the punch. This is Our Protagonist Rin. Oddly enough, Rin is not by nature a brawler, things just seem to happen that way. In this case, Rin had seen some boys torturing a bird so he decided to step in and stop them (which results in his losing his job as a delivery boy because he was late).
Later, Rin is in a confessional being interrogated by his confessor. He is extremely disgruntled about it because the priest he is confessing to is also his adoptive father. He is also lying about how he got injured which results in exasperated scolding from the priest (who is also slightly disreputable in behavior and appearance). Shiro is less than happy with his adoptive son, who has once again lost his job. Rin appears to have some self-esteem issues due to having lost so many jobs and seems to believe that he’s just inherently unable to keep a job (which results in another scolding from his dad for being so down on himself).
As a contrast, we meet Rin’s younger twin brother Yukio, who is getting ready to go to an exclusive school called “The True Heart Academy.” Yukio greets his brother with a “oh, you got into another fight, Rin,” prompting Rin to tell Yukio to shut up. Everyone seems to think it’s extremely funny that Yukio is so responsible and successful while Rin is disreputable, a bad student and constantly in trouble. Rin of course is the only one who thinks it definitely isn’t funny. He snaps back at the monk and something strange happens–a heater bursts into blue flames. Shiro fusses about needing to replace the heater, but the scene seems a little suspicious.
Yukio and Rin have a little heart to heart chat. Rin is very enthusiastic about his brother going to school to become a doctor, and they talk about Yukio going to school. Yukio seems worried about Rin, who has been having so many problems, and can’t seem to hold down a part time job. Rin defends himself, saying that he is worried about the problems he has been having as well. The conversation is interrupted by two of the monks who have brought a help wanted ad for Rin.
In the next scene, we learn that Rin really does not interview very well at all. He does seem able to do the work however, so he manages to get hired. Unfortunately, while he is heading home he sees a strange little monster that has stolen a little girl’s scarf. When he goes chasing after it, the monster ends up knocking over a display resulting in Rin getting himself fired on the same day he got hired (which is extremely unfair of the manager, considering Rin managed to keep the little girl from getting squished by the same display).
Back at the monastery dinner is getting cold because Rin hasn’t shown up yet. Yukio heads out to look for him and finds him in the park. They have another conversation, and Rin confesses he lost his job again. Yukio wants to know what happened, but the weird little monster that turned up is something Rin can’t really explain, so he doesn’t even try. They have a brief argument, and then they both head off.
When they reach the monastery, they see Shiro talking to a man who turns out to be the little girl’s father. He thanks Rin for helping her, saying that his daughter is very absentminded and clumsy. Rin immediately defends the little girl, saying that it is not her fault–she is being tormented. The father thinks that Rin is referring to human bullies instead of little floating gremlins and walks off with his daughter in tow, trying to coax his daughter into naming the bullies. (Shiro meanwhile is very startled that Rin saw the little floating monster.) Shiro talks to the father and the father and daughter head off. Then Shiro scolds Rin for having lost yet another job, grounds him, and sends him to bed without supper.
Later, we see Shiro heading down into the cellar. He opens a locked chest of drawers and inside is a sword and scabbard. It’s lying on a red cloth that looks as if it had been used as an additional covering for the sword. Shiro seems surprised to see the sword unwrapped. He says “just as I thought,” and the scene fades to black.
The next morning Rin wakes up and sees a good-bye note from his brother (which ends with a post script warning Rin to not make their dad worry). Rin grumbles about Yukio heading off without telling him goodbye in person and heads to the window where he sees hundreds of thousands of tiny little monsters floating in the air. He runs outside, trying to see what’s going on and sees people going about their daily errands without appearing to notice the little floating monsters.
Rin of course, thinks he is going crazy. The situation gets even worse and weirder when the jerk that was shooting pigeons earlier turns up. The jerk and his friends are literally swarming with the tiny monsters. Since the jerk is going to be attending the True Cross Academy and his family is an important one he wants to try to bribe Rin into keeping his mouth shut about what the jerk and his friends had been doing. Rin says he does not care and does not want the money. The jerk keeps pushing at Rin which results in Rin punching him again. Then there are even more monsters swarming in the air around the jerk, who promptly grows fangs and claws and attacks Rin.
Things do not look good for Rin, but then everyone bursts into blue flame (that doesn’t burn him). The jerk introduces himself as Astaroth (or rather, the demon currently residing in the jerk introduces himself as Astaroth). Astaroth refers to Rin as a scion of Satan and a prince, much to Rin’s bewilderment. Then Shiro turns up and casts out the demon that had possessed the jerk. He then gives Rin a quick rundown of the situation. Shiro Explains that the little monsters are called “Coal Tar,” and that there are two worlds–Assiah, and Gehenna. He also explains that Rin is in fact the son of Satan and every demon in Gehenna will want to kidnap him for a variety of reasons now that Rin’s powers have awakened.
Rin is quite understandably traumatized by all of this information and we end the episode focused on Rin’s horrified expression.