Sei Godaīn (醐醍院 誠 Godaīn Sei) is a student who attends True Cross Academy.
Sei is a young man of average height with short, slightly unkempt black hair and large, dark eyes. Usually seen with a worried expression etched upon his face, Sei dresses in the uniform that is expected to be worn of every male True Cross Academy student: a short-sleeved white dress shirt, black dress pants, black socks, black dress shoes and a striped tie. On his person, Sei also carries a light-colored bag in which his school supplies are located.
Sei is a very friendly young man, having gotten along with Rin Okumura mere moments after having properly spoken to him. He is also rather polite; he addresses Rin with the "-kun" suffix and properly thanks him for his help. However, Sei also fears things he doesn't understand, such as Demons, and becomes very defeatist when he can't figure out a way to deal with something.
Though not much is known about Sei's personal past, he was exposed to Miasma at an undisclosed time over the summer holidays, rendering him able to see Demons.
True Cross Academy Festival arc
Sitting in class, Sei sees a Demon traveling towards him across the classroom, causing him to panic and disrupt class. When asked by the teacher what's wrong, Sei exasperatedly responds that he was dreaming, earning him a quick remark from the teacher about the summer holiday mood. Sitting back down at his desk in fear, Sei watches as the Demon continues to travel about the room.
After class, Sei, still traumatized from his earlier experience, watches as the same Demon roams through the hallways. Petrified, Sei can only stare at the black monster, but his gaze is averted by Rin, who tells Sei to stop looking into its eyes. Taken aback, Sei quickly asks Rin if he, too, can see the Demon, to which he is told yes and that he must simply ignore kinds such as that. Sei is then told by Rin to follow him, which he does; outside the school the two sit down. Sei tells Rin that he thought he was going insane and asks him if they're the only ones who can see Demons, which Rin explains that they are not, something that takes Sei by surprise. When asked by Rin if he has been injured lately, Sei curiously responds that he hasn't been injured in ages; thinking rather hard, Sei wonders aloud if his problem is due to the True Cross Academy's seven mysteries. Sei then continues by explain to Rin that they became a popular topic over the summer, which was approximately around the time he began to see Demons. Curious, Sei questions Rin as to when he was able to see Demons, which Rin responds to by saying that he's an apprentice Exorcist, confirming Sei's suspicion that what he saw was indeed a Demon.
Taking all the information in, Sei tells Rin that it feels like he's having a nightmare before putting his head in hands, whereupon he states that he doesn't know if he'll be able to live the rest of his life with the ability to see Demons; Rin reassures him by stating that he'll talk to one of his teachers about his problem, something which relieves Sei and prompts him to thank Rin, calling him a nice person. However, Sei quickly follows up by stating that he thought Rin was a delinquent, a fact which Rin bashfully doesn't deny. Just then Rin states that he must go to Cram School and Sei bids his new friend farewell, wishing him good luck in his Exorcist studies. The next day, however, Sei begins to scream in the school hallways, begging for people to stay away from him. When he sees Rin running towards him, Sei, with a terrified look, calls out to him and runs in his direction before falling down, completely petrified of the Demon that is chasing him; Sei pleads for Rin to help him. It is then that, as Rin sends the Demon scurrying away, that Sei sees Rin's tail reveal itself. Unable to handle what is happening around him, Sei, laying upon the floor in the fetal position, declares in a broken voice that he can no longer handle everything and begs, once more, for help.
As he lays in the infirmary, Sei is told by Rin that if he continues to act scared like he is then Demons will continue to chase after him, causing Sei to admit that he must be a weak person for being able to see Demons. As he calls out that he wants his old self back, Rin leaves, demanding that Sei wait for him there; as he walks, Sei once again sees Rin's tail.
Several days later, Sei returns to school where he meets up with Rin, to whom he admits that even though he's scared he can't keep missing classes. Sei then tells Rin, rather innocently, that he thought that he saw Rin with a tail not too long ago; Rin's tail appears once again and he admits that he's half-Demon, greatly shocking Sei. Sei remains completely fearful of Rin as he happily claims that soon he'll have the eyedrops that will make him unable to see Demons. Sei is then forcefully clapped by Rin, which the latter apologizes for, but Sei himself apologizes and leaves Rin, quivering. That night, Sei is called by his roommate to see a visitor at their door: Rin; he hands Sei the eyedrops happily and tells him that he's happy for him before attempting to leave. Sei then stops Rin and asks him what his situation is if he's half-Demon, as well as if he's scared, to which Rin says yes he is, but that he has friends and family to support him. Sei then watches as Rin leaves his front steps; when he's gone, Sei sadly looks down at the eyedrops.
Some time later, as a Demon wanders around the classroom once more, Sei approaches Rin and tells him this fact, surprising the young Exorcist. When asked by a shocked Rin as to why he can still see Demons, Sei states that he didn't use the eyedrops but that he still wishes to keep them just in case. Sei is then immediately asked if he's scared; Sei replies that he is, but that he too has friends, a family and dreams supporting him. Patting Rin's shoulder, Sei tells him that if anything comes up, he'll personally request his help. Flabbergasted, Rin then begins to comedically yell at Sei, stating that he worked exceptionally hard to obtain the eyedrops, a thing which Sei lightheartedly jokes at, slightly annoying Rin.
With the school festival now around the corner and his class in charge of procuring the light meals, Sei pitches pork miso soup and rice balls as there will be chain stores setting up shop at the festival and they will need to compete; this makes Rin excited, and Sei quickly learns that Rin is an accomplished cook. After class, Sei walks with Rin still surprised that the soup and rice balls were chosen; he explains that the True Cross Academy Festival is a grand event that is widely broadcast. With Rin excited over the festival, Sei states that he is too, but that he's a little depressed over the dance party portion. Answering Rin's confusion, Sei points to a nearby poster that explains that on the second night of the festival, there will be a student-only boy-girl music festival.
Later on in the week, the festival begins and Sei watches in amazement as Rin effectively mass-produces a multitude of rice balls by hand, and then gives him a thumbs up when they are proven to be delicious. However, with their food proven to be extremely popular, Sei soon begins to become weary as he takes the orders of the many people lined up outside his class' shop. When even the principal himself takes a liking to their food, Sei happily celebrates with Rin whilst congratulating him for his superb cooking, though he worries about the number of workers they'll have tomorrow, as the dance festival will involve a majority of their classmates. The next night, during the hustle and bustle of the dance party, Sei tells Rin to go have fun as he's worked exceptionally hard. As Rin leaves, Sei agrees to tell him if Izumo comes by to help.
Powers & Abilities
Spectral Awareness: Having been exposed to Miasma, Sei is among those who can see, and interact with, Demons.