Kurogane Taito is a freshman in Miyasaka High. After an injury in his leg(snapped tendon) that prevented him from practicing karate, which he excelled in since elementary school, he had always believed that he was an ordinary, regular guy. However, due to a forgotten promise exchanged with a beautiful Vampire (Most Ancient Sorcerer) Saitohimea nine years ago, he was in fact no longer ordinary. Nine years ago, he was injected with Saitohimea's poison, which prevented him from dying as long as he didn't die seven times within fifteen minutes. Shortly after his change, A boy named Kurenai Hinata attacked them with a demon and killed Taito six times. In order to prevent Taito from dying, Saitohimea agreed to leave with Hinata and have Taito's memory wiped. As a result, Saitohimea was experimented on and imprisoned within a world with no sound or light whatsoever, and Taito continued with his life as a normal human until his freshman year in high school.
Hinata appears to Haruka. Haruka is actually an observer sent by the monsters on the other side of the moon. He was thinking of using her against her masters, but it seems that she may be planning on rebelling against them. Saitohimea suddenly drags Taito away to bring him on a date. An unknown male and female were watching their conversation nearby. Taito wants to become stronger and tries to unsuccessfully ask Gekkou for help. A guy dressed in a black suits enters the school and seems to be talking to a blue haired girl who suddenly just disappears. The guy is revealed to be Cross Philier Yuuichi, the new English teacher and Student Council advisor. Meanwhile, Saitohimea has almost dragged Taito out of the school before he apologizes that he can't go on a date and excuses himself saying that he had some plans for the day. Actually he was planning on training at the fight clubs and it seems that he has actually gotten stronger to the point that world fighters can't compete with him. Meanwhile Gekkou and Mirai are told about magical traps in the city and they go to several places, which seems to Mirai as if they're on a proper date. They meet Taito who is on his way back and Mirai tells his Saitohimea was crying. Taito realizes his mistakes and runs back to be with Saitohimea.
Gekkou and Mirai start fighing Taito and Himea, but are interrupted by Gekkou's brother Hinata. Taito uses up all six of his lives and seemingly dies while Himea screams his name and he wakes back up in class. "The new tranfer student" Himea walks into class and jumps onto him, knocking both of them to the floor while everyone else is blushing. Haruka is shocked. They meet Gekkou and Mirai, and Gekkou tells them they are going to be his "slaves" and work with them in the student council. Himea tells Taito they will be together foever while she clings to his arm.
Taito wants to become stronger so he can protect Saitohimea. Gekkou sends him off to meet Eduluca who will grant any wish but takes "payment" of equal value. Before he makes his wish, Taito learns that Saitohimea came to Eduluca when he had died previously and exchanged a large amount of her power to revive him. Taito wishes to become strong but only through his own power. Eduluca is disappointed but grants his wish by planting within him a lot of useful and useless information but still takes something important to Taito though doesn't reveal what it is. Saitohimea offers to help Taito search for something helpful within the amount of information he was given, wherein Taito meets and forms a contract with Vishoub Eleranka. Meanwhile Cross appears in the Student Council room to reveal that the military has commissioned him to keep an eye on things. Gekkou calls the military incompetent and Cross reveals his superior speed to aggravate him into a scuffle and show him that he isn't as powerful as he thought himself to be.
Kurogane Taito continues to have a recurring dream. A 6 year old Taito sees a girl who he cannot remember while they sit together in the playground. She tells him that she will give him her poison and afterwards they will always be together, enticing him when he becomes frightened with comforting words. After biting him and giving him her poison, the girl confesses her love to him and encourages him to tell her he loves her as well, thus sealing the curse. Taito is then woken up as a high schooler by Shigure Haruka, whom we realize is a long time friend and a girl who has a crush on Taito. After a school day that includes bumping into the most popular boy in school, the cold hearted Kurenai Gekkou, Taito and Haruka split ways as Taito heads home. As he's crossing the street, he notices a sleeping truck driver headed straight for Andou Mirai, Gekkou's apparent subordinate, and jumps forward to push her out of the way only to be hit himself, an obvious killing blow... until Taito's head begins speaking to Mirai and his body stands by itself, grabbing the head and running off in a panic. As Taito frantically worries he suddenly remembers who the girl from his dream is, Saito Himea, the girl who enslaved him when he was younger and was taken away by a man who left Taito with no memories of Himea. When Taito speaks her name, she is released from her prison, turns into a sixteen year old and meets Taito at the playground from their youth. Gekkou arrives and stabs Himea through the chest, ending their long awaited reunion.
The summer holidays brings with it the summer heat! And so, Haruka decides to invite Taito to the public baths. Coincidentally, Izumi convinces Saitohimea to go as well and they meet Gekkou, Mirai and even Hasga and Serge there too. Hilarities then ensue. Meanwhile, Cross in a monologue reveals that the mysterious girl he was talking to in an earlier episode is called Liir and is currently with the student president and that the dark rabbit within Taito might awaken soon. Also seen in a monologue is Hinata, who talks to himself saying that his brother might actually be able to do something about the prophecy. After the baths, Taito and the rest of the group jump into a portal and leaves the series in a cliffhanger.
Taito is torn between having lunch with Saitohimea or eating the meal that Haruka prepared. Luckily, he is saved by a call from Gekkou as insects have invaded the school and school has been cancelled for the day. It turns out that the school is situated in a place where portals from multiple dimension intersect and that the military are in charge of the area but no one over 18 can get into the area because of a barrier. Mirai is disappointed that swim classes were cancelled due to the bugs, and forces the others to join her at the pool but Gekkou walks off to the Student Council room. Mirai reveals to Taito how she was forced to contract with Gekkou. At the Student Council Room, Gekkou meets a messenger from the Tenma. The sky turns black, and the moon starts to glow while it starts to rain red liquid.
It seems that Haruka was asked by Cross to cook for the whole group. This leads to a lot of tension due to the love triangle between Taito, Saitohimea and Haruka. Izumi tries to cheer up Saitohimea and suggests the group have a test of courage event. Izumi thought she made sure that Saitohimea would get paired with Taito, but Cross interfered so he could pair with Taito. He pats Taito on the way back... and a dark demonic figure seems to awaken within Taito. The group finishes the night with fireworks, where Haruka confesses her feelings to Taito.
While traveling, Saeko's vehicle is attacked and Haruka has been kidnapped by two male magic wielders called spellbreakers. Cross refuses to let Taito and the rest rescue her, saying that it's now a military matter. One of the spellbreakers appears to Saitohimea while she is alone and offers to release Haruka if she would surrender herself to them. Izumi tries to talk her out of it and then goes to Taito when she fails. She turns herself in to the spellbreakers, but they trap her instead and refuse Haruka. Taito and Gekkou then assault the school to open a gate to where the spellbreakers are. Meanwhile, while they assault the school it is revealed that the observer personality of Haruka's was the one who commissioned the spellbreakers. She promised to give them her knowledge about the Tenma if they would destroy the observer personality, seal up Saitohimea and then return her other self back to Taito.
Since Balhskra is gone, instead Bliss has taken over Saitohimea's body. Bliss is a spell that Saitohimea created when she was lonely a long, long time ago. Meanwhile, Gekkou meets with Tenma who states that the "witch was broken due to solitude" and reveals to him a prophecy where "Ramiel Lilith would destroy the world". Tenma gives him the power to stop Ramiel in exchange that they would not interfere with his "underlings". It seems that Saitohimea was hurting because she was unsure of Taito's feelings. Himea and Taito finally kiss and Taito finally reveals his feelings for Himea. Gekkou confronts Himea to see if she knows anything about Ramiel, but it seems like she doesn't. During this episode, Haruka is out shopping so she can make meals for Taito and at the end sees Hinata alive and well, waiting for her in front of her home.
A portal appears that supposedly leads to Tenma, and Gekkou and Mirai jump in. Saitohimea gets possessed by the red liquid, which is revealed to be Bahlskra. Bahlskra tries to permanently kill Taito because he is concerned for Saitohimea, but Saitohimea believes that Taito is the only one who can save her as he is not stained like they are. She then destroys Bahlskra. At the end, the Tenma is conversing with their observer on Earth who was created for the sole purpose so that Saitohimea does not complete the sacred spell, Bliss. The observer is revealed to be none other than Haruka, but she herself does not realize her dual life.
The group has arrived at a beach, which is meant to be an intensive training camp and even Izumi was invited to come. Cross tests out their limits and announces that each of them should become powerful enough even to beat ancient dragons. He also states that they would each be tested at the end and won't be able to leave the area's barrier if they fail. Cross thought he had everything planned out thinking that Izumi could be their cook... but after several days of eating curry for breakfast, lunch and dinner, decides to call for some help. During their break, Taito and the others are surprised by the appearance of Haruka.
Gekkou and Mirai fight with Cross while Taito makes his way to save Haruka and Saitohimea. The fight ends up with Cross threatening to kill Mirai and Gekkou bowing his head to Cross and asking him to spare her. Hinata appears and mocks his brother and Cross, and states that he knows all about the prophecy and that they are not even near his power level. Taito fights Hasga while Serge continues to seal up Saitohimea, even though they offer to let Taito return home with Haruka. Nyankichi shows up for a second, tells Taito to curse magic and disappears... even though his spell seemed to have no effect. Taito gets beaten to the point that he will permanently die, but continues to struggle and the two spellbreakers are reminded of when they were young kids in a similar situation. Gekkou arrives to help, but Taito refuses his help even though he uses his last drop of stamina to barely lightly punch Hasga. Saitohimea then wakes up, as Taito's spell seemed to have allowed her to analyze and counter Serge's sealing spell. She almost kills the two spellbreakers, but Taito asks that they just go home. Haruka seems to be fine, but without her other personality. The spellbreakers end up joining the school.