Epigraph of the Closed Curve

Heijikyokusen no Epigraph (閉時曲線のエピグラフ) is the first installment in the Epigraph Trilogy series of light novels, taking place during November 2010 in the Beta Attractor Field. The light novel has been adapted into a manga with two volumes being released in early 2014. The limited edition release was bundled with the Drama CD Shaei Kyokumen no Epitaxy.

The title is a reference to the "Closed timelike curve (CTC)" in mathematical physics.

Summary
Though the world keeps turning as always, the international race to build a time machine has begun after Dr. Nakabachi defected to Russia with Makise Kurisu's time travel thesis.

Only a few months after he failed to save Kurisu, Rintaro Okabe meets Maho Hiyajo, Kurisu's senior from her American university with whom she had been researching the A.I. Amadeus.

Plot
The following plot summary is based off of the manga adaptation. Reader discretion is advised.

Part 1
In November, 2010 news reports of a new type of encephalitis as the explanation for the wide-spread experiences of déjà vu last summer are being broadcasted in Japan, encouraging those with such experiences to seek medical advice. Mayuri's cosplay friends Kaede and Fubuki, who had had many dreams of Mayuri dying, consider doing so. Dr. Nakabachi is also seen on the news decked with medals and honor in Russia, though according to Amane Suzuha he is actually kept under house arrest.

Meanwhile, Rintaro Okabe is greatly affected by the traumatic experiences of the summer. He suffers from severe PTSD, has abandoned his alter ego as the "Mad Scientist Hououin Kyouma", has thrown himself into university life, and avoids visiting the lab. Shiina Mayuri, who had shielded him from Suzuha's pressing him to try again after the first disastrous attempt to save Makise Kurisu, has stuck by his side, but though Okabe is doing his best to live like an ordinary person, she and the other lab members are saddened to see him in so much pain and miss his old self.

Suzuha, on the other hand, is living at the lab, and her frustration and worry are almost palpable. In 2036, after Mayuri had given her adoptive daughter Shiina Kagari her long-treasured necklace made from a Metal Upa, Mayuri had entrusted Kagari to Suzuha, and Mayuri and Suzuha's father, Hashida Itaru, had seen the two off as they time traveled to the past moments before the Japanese SDF could stop them. However, almost three months since arriving in Akihabara 2010, Suzuha was stuck here without Kagari and unable to convince her Uncle Okarin to try again. She was unable to do anything, though the international race to build a time machine had already begun that would bring about WWIII; and kept trying to avoid contact with her mother Amane Yuki, whom Daru had met at the Comima that summer, in case it might cause a time paradox.

Her attempts to remain unknown fail, however, one evening when Amane Yuki comes over to the lab and Mayuri coincidentally manages to convince Okabe to visit as well. Okabe accidentally finds Suzuha hiding behind the workroom's curtain and Suzuha ends up being introduced to Yuki as Daru's younger sister.

Daru is thrilled to have met Yuki but also self-conscious and shy about approaching her to the point where Yuki sometimes sadly wonders if he is avoiding her.

Okabe has been helping with the organizing of the ATF (Akihabara Techno Forum) where the professor from his tennis circle, named Izaki, is holding a seminar on "Pseudoscience and the Nakabachi Theorem", apparently analyzing Nakabachi's claims that Russia has made public. On the day of the ATF, he meets Maho Hiyajo and realizes that she is from the same American university institute as Kurisu had been, Victor Chondria University Institute of Neuroscience. Maho has come with her professor, Alexis Leskinen, to act as his interpreter and help present their research in artificial intelligence. However, before Leskinen's presentation begins, Okabe is greatly shaken by seeing Kiryuu Moeka come to interview Maho as a reporter, and his interest is caught when he overhears Kurisu's name when Maho and Leskinen are later discussing in private in English how the FBI had come for unknown reasons to their university lab after the late Kurisu's home had burned down.

Leskinen and Maho start their seminar with an introduction to Kurisu's previously published thesis "The Analysis of Nerve Pulse Signal on the Memory That Accumulated in the Temporal Lobe." Their institute had continued the research and was working on applying it in two directions. One was the medical use of making "memory back-ups", which would allow people to restore their memories if lost due to illness or old-age.

The audience, however, becomes abuzz with skeptical murmurings, and before Maho can continue on to the second application of the research, a man with glasses stands up and begins declaring that they are committing blasphemy by messing with the human mind. He continues to speak extremely insultingly about Makise Kurisu, even claiming that her death was heavenly punishment.

Okabe, who was sitting with Kaede and Yuki, had begun crying when he saw Kurisu's research, which had been the basis for her Time Leap Machine, continued. He could not contain himself while she was being slandered and jumped to his feet shouting "Objection!" startling everyone in the room. In his fervor he loudly tells the man that no reason is acceptable to deny a person's dreams and curiosity and the rest of the audience that many things were thought impossible in the past until scientists realized them. Though Leskinen cautions Okabe to be calm as a scientist, he is delighted with the things that Okabe just said and leads the room to give him a round of applause as Okabe becomes embarrassed by the attention and realizing that for the third time he has lost his self-control when he hears someone bad-mouthing Kurisu.

After that Leskinen and Maho continue on to their second project the "Amadeus System". A life-like reproduction of Maho appears on the room's projection screen, introducing herself as an externally-stored version of Maho recorded 78 hours and 32 minutes previously and declaring herself ready to prove to the audience that memory data can be turned into digital data. As Leskinen and the Amadeus Maho begin to converse the audience is shocked by the A.I. refusing to talk about personal secrets as if it can feel shame and wariness. Okabe explains everyone's surprise to Kaede and Yuki as that if this is not a preorganized performance then it means that the program has memory functions. This is, however, a risky project morally as there are many who feel a taboo towards robotic and A.I. research. Leskinen cuts through the audience's murmuring to drop the bomb that Amadeus is like the human mind in the way it handles data output and input allowing it to judge for itself what to say or not and its imitation of emotion and memories is good enough to be capable of lying. He declares that he does not believe lying is a good thing but by testing in this way they believe that "Amadeus" will become able to produce real human thoughts and ends with the declaration that they might have developed a program with a "soul".

Part 2
Okabe's professor, Izaki, had invited him earlier in the day to join the after-party for the forum. That evening as Okabe is at the lab to get suited up for the formal event, he cannot contain his excitement over the interesting seminar held by Leskinen and Maho. Mayuri listens to him with a happy smile on her face and Daru feels torn. However, Suzuha's face darkens, though she refrains from saying anything, upon hearing that Okabe wants to go for an exchange year at the Victor Chondria University.

At the after-party Okabe and Maho, who are both ill-at-ease at such a social event, encounter each other on the sidelines. When Okabe apologizes for making a ruckus at the seminar, Maho thanks him, explaining that she was on the verge of an outburst herself, because her lab junior was someone special to her. As their conversation turns to her institute's research and Kurisu, Maho is surprised at the depth of which Kurisu discussed her theories with Okabe and is so happy and relieved that Okabe was Kurisu's friend, thinking that Kurisu did not die while lonely in Japan.

Maho had been against sending Kurisu to Japan, but their professor had encouraged otherwise. After Kurisu's thesis was published in Sciency, both the positive and negative reactions of those around them caused Kurisu to be even more singled out in the institute, so Leskinen argued with Maho that it would be good for Kurisu to get away from there for awhile and was in favor of her going to Japan. Even up till Kurisu's departure Kurisu had been actively thinking up new things for their research such as giving Amadeus the ability to talk to itself, the study of which could be useful to medicine and which might work as proof of the program feeling pride. As Maho thinks of these things, she involuntarily begins to cry.

Later, outside the party hall she apologizes but Okabe assures her that he has not gotten over the loss of Kurisu either. Okabe carefully asks Maho what she and Leskinen were discussing so seriously about earlier when he overheard Kurisu's name. She tells him that they had had a call from Kurisu's mother some days ago, because her house burned down. Fortunately, Kurisu's mother was away from home at the time, but a neighbor had seen a stranger searching through the house and afterwards the fire had started.

She tells him that other strange things have occurred as well. Shortly after Kurisu's death, Japan's policemen and a detective had come to the institute. They told them that there will be a joint Japan-American investigation into the case and asked for their cooperation. However, Maho and Leskinen thought it unusual when the officers wanted to take all of Kurisu's belongings and view her research data, so the professor called Japan to confirm. He was told that no such joint investigation was in place. The Japanese had sent no detectives, and the American police were not involved in the case. However, by that time it was too late as the shady men had already disappeared.

Maho has her doubts. Though she has been told that the Japanese police believe that Kurisu was targeted by an overseas group of thieves, she feels that everything that has been happening is just too strange. Kurisu must have been the target of a much larger group and was murdered. She wants to know the truth behind Kurisu's death and asks Okabe if he knows anything.

Okabe shakes violently as the thoughts and memories of Kurisu and her death flood in. He is stuck as he struggles out an answer of wishing to know the truth as well but believing that they will catch the criminal soon. She dearly cares about Kurisu, but he is unable to tell Maho about the time machine and the future but also unable to tell her that he is Kurisu's murderer to explain why he was there at the scene. That is why he has to act as if he knows nothing.

Pushed to the edge by his recollections of Kurisu's death, his panic attack worsens. Seeing him suffering, Maho worriedly apologizes for getting so worked up, remembering that he is hurting too. Okabe can only regretfully think his apology to Maho.

Part 3
As Maho stands up from the couch she and Okabe are seated on, she trips and becomes flustered when Okabe catches her.

On their way back to the party, she tells him that she and Leskinen will be staying in Japan for awhile to prepare for their next research project. Feeling that the professor will surely give his approval if it is Okabe, Maho offers to show Okabe Amadeus again, telling him that they have the memories of one other scientist saved, that of Makise Kurisu eight months ago.

Later, in the venue's parking garage as Okabe is saying good-bye to Maho and Leskinen who sit in the back of Ozaki's car being given a lift, Ozaki, to Okabe's inner disgust, suggests that Okabe could try to romance Maho as having a strong connection at a prestigious, overseas institute could help boost Okabe's academic career.

Suddenly, the man with glasses from earlier during the seminar appears looking deranged and holding a firearm with silencer. He quotes excerpts from the Bible Matthew 18 and declares that the soul will never live in silicon! He shoots at Ozaki first, who sustains a bleeding graze wound to the shoulder while running away. Okabe grabs Ozaki's dropped car key and, despite not knowing how to drive, jumps in the car that Leskinen and Maho are sitting in to try to drive them to safety. The man shoots again this time grazing Okabe's head. Despite his bleeding, Okabe does his best to get them away. However, because he doesn't know how to operate the car properly, Maho, who is an expert at driving, slings her body over the front seats' armrest to operate the shift stick. When the crazed man pursues them in his own car and is about to hit them, Okabe quickly pulls her onto his lap to protect her from the impact, but she takes the wheel and a dangerous car chase ensues instead.

Having outrun their pursuer and reached the parking garage's exit, they are forced to a stop. Suddenly self-conscious again of the fact that she is sitting in Okabe's embrace, Maho and Okabe start bickering about sexual harassment until Prof. Leskinen calls them to look out because their attacker is coming at them. They jump out of the car just in time to avoid injury as the other car crashes into theirs and ignites.

The three are all safe and help arrives. After discovering Okabe's head wound, Maho and Leskinen are relieved to find that it isn't severe. However, the insane man drags his burning body out of his car to try to attack them again. Cursing them as infidels, he shoots at Professor Leskinen.

On the rooftop of the Radio Kaikan Building, Daru examines the time machine in frustration. Faris appears having brought cake intending to give Daru a snack, but Suzuha had caught on to them and is not happy. Suzuha had told Daru before to not try to study the time machine, since the world line convergence will not allow him to build one in this age anyway or it could cause a time paradox. Also, she has been doing her best to keep her promise with her father from 2036 to make him eat healthier and exercise more so that he will slim down while he is younger, but it hasn't been easy to get Daru to change his habits.

Faris tries to mollify Suzuha with her favorite cake and almost succeeds when Suzuha notices that someone is observing them from the stairs. She chases after the lithe figure with long hair. However, the person is highly trained and reads her movements and line of fire, successfully getting down the stairs and away on a motorbike.

Faris and Daru catch up to Suzuha outside. Suzuha is worried that the time machine has been discovered, but Daru and Faris reason that anyone who is not a lab member would not have been able to understand their conversation. However, Suzuha tells them with pain that there is one other person who is not a labmem but who knows about the time machine as she looks darkly at the night sky.

Main characters

 * Rintaro Okabe
 * Maho Hiyajo
 * Suzuha Amane
 * Daru

Supporting characters

 * Alexis Leskinen
 * Amadeus
 * Mayuri Shiina
 * Faris NyanNyan
 * Luka Urushibara
 * Moeka Kiryu
 * Yuki Amane
 * Fubuki
 * Kaede Kurushima
 * Kagari Shiina
 * Izaki

Release
The light novel was first published on November 9, 2012 by 5pb./GigasDrop, with a limited edition release coninciding. It was written by Masashi Takimoto, the scenario writer for My Darling's Embrace. The cover was illustrated by huke, while the text illustrations were done by Yasuhiro Ikeda.

It was later re-published bundled into a box set with the rest of the trilogy on September 26, 2013.

Manga adaptation
The manga adaptation was illustrated by Tadasu Yoshida. It ran from February to December 2013 in the free web comic magazine Famitsu Comic Clear. It was compiled into two volumes published in both physical and digital forms by KADOKAWA / Enterbrain BC.

Dramatization
On December 28th, 2014 at the Winter Comiket 87, 5pb. released an audio drama containing select scenes from the light novel.