Magia Record Story Rondo of Oblivion Sleeps for Eternity
The following is a summary posted on 4chan's /pmmm/ general.
Mikura is able to fine any historical artifact or sites she wants, so she is able to find the diary of the story's main character, which detailed his love for the heroine. Mikura's innate magic ensures she can deliver her story to those who need them most, and Yukika, who was hired for a role in the movie, ensures that weird stuff will happen due to her innate magic.
It seems the movie draws the soul of the actual heroine who killed the hero and herself when she thought he only chose her because he lost the memory of his childhood sweetheart in real life, but the truth is that the main character saw that as playing house, and his heart was with the heroine when he sees her for the first time.
This results in the heroine possessing Seira, who is portraying her in real life, learning the truth that she killed her lover based on false assumptions.
News of the movie shooting spread, and some in the East twist it into a story about how Ria bullied Riko so hard that she cried. Tension rises between magical girls from the West and East at an abnormal speed, eventually leading to Kanagi trying to get justice for Riko by punishing Ria, and Yachiyo defending Ria from this.
The Mikura trio rush to the scene since they believe their insensitivity in choosing the theme caused the troubles but they could not stop the fight. It takes Yukika bringing in Mitama and Mifuyu to snap Yachiyo, Kanagi, Ria, Riko and Tsukasa out of their trance. According to Yachiyo and Kanagi, they had met up to understand what is actually happening, but they lost control when they saw each other, only having the thought of crushing the other side. Temari notes that Kanagi was reprimanding Mikura for stopping the fight using the name of the main character she was cast for. Mikura is knocked out cold since she tried to stop the fight, and Seira who arrived late began crying as she tends to Mikura, also calling her by the name of the main character. Everyone then heads to Mitama's place to assess the situation.
Iroha heals everyone involved, but Seira ended up crying until she lost consciousness. Mikura and Temari shared what they have done during the shooting, and Nemu who came to help Iroha gave a hypothesis to the situation:
It is an unfortunate chain reaction from the various innate magics and a lack of in-depth understanding of them. Seira's actual innate is letting actors in movies she direct be absorbed into their role, becoming the characters in the movie. Temari can influence people to act like how she writes them to be, while Mikura actually resurrects the history from historical artifacts she finds.
Thus, the movie they made together resurrected the hate (worse then what we have now) between the West and East, and the matters worsened when the script ended up being a tragedy. Everyone is deeply caught up in their role, creating a split personality they aren't even aware of. Temari can only passively influence people who are alive, but since the actors have a persona created to act for the movie thanks to Seira's innate, she can easily influence them to act like her script which is real stuff that happened in the past and resurrected by Mikura's innate. Thus, the main character and heroine's personas came alive in Seira and Mikura. In addition, Seira's innate also turned the whole of Kamihama into the stage of the movie, so unless she calls it finish, the situation will only become worse. Nemu warns Temari to be careful of her innate since her being a cripple is an example of losing control. Things will be fine if she writes fiction though.
Unfortunately, the heroine took over Seira's body and bolts, but Mikura and Temari get help from Iroha who promised them that the Magia Union will help. They decide not to call the cops yet since it will be difficult to explain everything and the time limit isn't up yet.
Back home, Temari learnt from Kyubey that the heroine was actually a magical girl before she met the main character. A romantic, she wants to have a beautiful relationship like the kind one would see in a happy romantic novel, but the main character being attacked by thugs hired by her relatives gave her a rude awakening, and thus she changed her wish which is born from a similar innate magic to what Temari has to restore the main character's memory and health. That broke her mind, and she eventually succumbed to the fear of losing the main character, leading to a double suicide. Kyubey notes that it is a pity that the energy went to waste, and informs Temari that she can remedy the situation if she tears her script. The price will be her sanity. This is when Temari realizes her losing conscious back in part 1 after editing her script is not due to overwork, but due to backlash for editing the effects of her innate magic. But she decides to put her life on the line for both Mikura and Seira, just in case.
Iroha's huge network in the Kamihama Magia Union proves to be great aid since they found Seira easily: she is seen near Kosho. They went to the room where they held her activities and was ambushed, the copy of the main character's diary stolen.
Temari is afraid that the heroine will act recklessly once she reads the truth, and Mikura is determined to put an end to this. She took the clothes she used acting as the main character with her as well just in case.
It is harder to find Seira the second time around, but the Union's huge network overcomes the problem and they find Seira at the mansion belonging to the main character, and also the place where they shot the movie. Mikura doesn't want to bother the Union further and decides to stop the heroine with her method, but Temari secretly prepares her actual script to tear just in case, and also called for her fellow actors to come to help.
Using herself as bait, Mikura dresses as the main character while Temari hides to one side. The other magical girls hide near the windows outside the mansion for easy entrance just in case. Temari sees Mikura shaking as she knows the heroine will knife her like how history and the script goes, and she has a trauma with bladed objects since she was kidnapped by strangers who used them when she was young.
However, Mikura insists that she face her fears instead of running, but the main character took over her body due to the respect for her resolve, and also because he thinks this situation should be solved by him instead.
The heroine arrives, and in tears she ask the main character for a dance. As they danced, they remembered the happy times they had, and the main character once again confesses to her that his love is true and he only has eyes for her. The heroine is touched and tears continue to flow, but she thinks she has done too much wrong and decides to commit suicide.
Temari and the other magical girls burst into action, but the heroine is easily stopped by the main character who comments that he would have done this back then if he wasn't dying on the floor. He whispers sweet words to her, convincing her to go in peace with him, while also letting go of the innocent girl she possessed. The heroine agrees to end this Tragic Waltz, and the main character apologizes for the trouble they have caused before disappearing.
Mikura and Seira regain control of their bodies, but before they can do anything, the mansion begins to burn, eventually destroying it and all historical records related the event. Seira informs everyone that the heroine used her innate and modified the burning of the mansion as part of the stage of the movie to end the tragedy.
Things went back to normal, though the history club did need to create something else to keep their club alive since they destroyed all records of the movie just in case the effect remains.
Despite this all, they learn more about their innate magics, make new friends in the form of the Union, and eventually acknowledge that they found a place where they can relax while doing when they like with company they want.
Note: Neither Mikura nor Temari live in Kamihama. They take the train to the city to study, and that's why they came into contact with Kyubey