After Mir was sealed away in the Crescent Chronicle thanks to the efforts of Shurelia and Tastiella De Lu's sacrifice, she continued her actions to destroy mankind by continually sending viruses and making them manifest in the real world through this place to attack the people. Due to this, the humans that had participated in the battle for sealing Mir away, the Apostles of Elemia, established the city of Platina just above the Symphonic Reactor and imposed upon themselves the mission of watching over the Reactor and annihilating any virus that came out from it.
At the start of Melody of Elemia, a new kind of virus called ELMA-DS showed up in the Reactor, and Knights of Elemia Lyner Barsett and Ayatane Michitaka were dispatched together with Shurelia to stop it. However, the virus had the ability to use Flip-Flop Conversion, making itself impervious to any attacks, while it also attacked them with a energy beam that damaged the Symphonic Power lines that gave energy to Platina, thus disabling their protection systems. Due to this, Shurelia and Lyner had to run away back to Platina and devise a plan while Ayatane stalled the ELMA-DS, while he also sealed off the Dividing Wall that gave access to the inner areas of the Reactor. However, the virus cornered both Lyner and Shurelia, forcing them to run away to the Gather. It was then that Shurelia told Lyner about the Hymn Crystal Purger, and after giving him a Hymn Brooch with a recording of the Purger's image and allowing him to borrow the airship that was stationed in the Gather, she sent him to the Wings of Horus to seek the crystal.
Shortly after Lyner and his newfound friends had found the crystal in the ruins of the Singing Hill, the viruses became far more active, and manipulating the Guardians that were supposed to protect the Tower, they mounted an offensive against the rest of the Knights of Elemia, finally breaching the security network that Platina was barely keeping functional at the moment. Upon getting word that the viruses were acting strange and that they had surrounded themselves in some sort of barrier that made Reyvateils feel sick, Shurelia stepped in and entered into the main room of the Reactor. It was then that she noticed that Mir had awakened once again, although only her voice could come out from the place in which she was sealed. Mir noted that Shurelia hadn't changed anything during all the time she was sealed, and after asking her why she sided with the humans, who she considered as the real viruses that destroyed Ar Ciel. Mir sucked one of the Knights that were near the Reactor and promptly disintigrated him to the shock of everyone present in the place. A Reyvateil that was present in the scene screamed that she didn't want any sort of Reyvateil-only paradise, while Shurelia told Mir that she wasn't going to allow her to continue sabotaging the Tower, to which Mir responded by announcing that she was going to host the greatest ceremony for the coming of the new world, and began by purging the Musical Corridor, making one of its seven plates fall to the Wings of Horus.
Shurelia remarked that these actions would disrupt the weather of the world and kill everything in it, to which Mir responded that she wasn't stupid and this was merely part of her plans, and after saying that there was a plan right behind Shurelia, waiting its time for being put into motion, she knocked out everyone with a flash of light. Ayatane arrived shortly later, and after checking out Shurelia's condition, he said that he would protect her to the end of his life, both as a Knight of Elemia, and to save his mother.
After undergoing the Circula Baptism at the Frozen Eye, Lyner and his friends found themselves near the Reactor, but before facing the viruses, they went to Platina in order to rest a little and to prepare themselves for the coming battles.
After the Download of the Purger was finished, Lyner took Aurica and the rest of the party to the main chamber of the Reactor while Misha waited safely in Platina. Once there, they saw Shurelia and Ayatane making a desperate last stand against the ELMA-DS, so Lyner rushed into the scene to help while Aurica began singing the Purger in order to allow the party to fight against the virus without any problems. However, once the battle ended, Aurica suddenly stopped singing and fell unconscious which forced everyone to go back to Platina to check her condition.
After the battle finally ended, Shurelia opened up the warp gate that was located further inside the Reactor, which led to the Frozen Eye, finally opening up the path between the Upper and Lower Worlds for the first time in centuries. This allowed both Lyner's group and the party searching for Misha's lost song to return to the Wings of Horus to carry out their own duties.
After the group found the Hymn Crystal Linker and Bishop Falss sent Lyner, Ayatane and Radolf Schnaizen to a mission which turned out to be a trap to dispose of them, Falss and his associate in crime, Bourd Rade, took several of their supporters with them and invaded Platina. They then took Aurica to the main chamber of the Reactor, and after forcing her roughly to position in the center of place, he ordered Aurica to begin singing Linker, without telling her that the song would trap her soul into the Binary Field and allow Mir to take possession of her body, instead using the excuse that this would allow Goddess Tyria to be reborn.
Upon arriving at the Reactor from the Frozen Eye, Lyner and his group heard Aurica's singing, and fearing the worst, they rushed to the main chamber, cutting their way through several Tenba guards and members of the Church of El Elemia, all supporters of Falss and Bourd. At the door, Radolf became worried for the state in which Platina would have been left due to this, and left the rest to Ayatane and Lyner. The two of them dispatched the rest of the guards that were lined in route to the center of the Reactor's room, but when Lyner tried to reach to Aurica, a barrier repelled him. Falss mocked him due to this reckless actions, telling him that Aurica's time in this world had already expired, and that she would soon become Mir, his puppet for ruling the world. However, through sheer force of will, Lyner managed to break through the barrier and reach Aurica, to the surprise of Falss and the amusement of Ayatane, who revealed that he too knew Falss' true name: Kyle Clancy. Once there, Lyner embraced Aurica and pleaded her to stop singing, to which Falss replied that Aurica didn't have a sense of self anymore. However, Aurica briefly awakened upon hearing the tender and comforting words that Lyner was dedicating to her, and regained her will to live. This was for naught, though, since Mir emerged shortly afterwards and expelled Lyner from the center of the reactor, while announcing her return. Falss stepped in, introducing himself as Mir's master, to which Mir responded by infecting him with viruses and telling him to prove himself worthy. Luckily enough, Misha began singing Chronicle Key a few seconds later, removing Mir's consciousness from Aurica's body and sending her back into her long sleep.
Ayatane then suggested running away to rest a little before confronting Falss. Lyner agreed with the decision, and after reuniting with Radolf and recovering fully, they returned to the Reactor's main chamber and challenged Falss. After a long and hard battle, Falss was defeated, but he merely mocked both Lyner and Radolf by saying that Mir's power was the power of civilization herself and the last hope they had for restoring the world to its former glory, but since they shattered that final hope, they deserved to rot away with the rest of the world. Then, he vanished away. Ayatane then asked Radolf for the status of Platina, to which Radolf responded that the Church knights had started a riot in the name of a Holy War. Shurelia, the Knights of Elemia and him managed to calm them down after several hardships, but the battle left the city in a very bad shape, to which Ayatane remarked how loyal Radolf was to the Church, despite them branding him as a traitor.
Peace had seemingly returned after all the chaos, but shortly later, viruses began pouring out from the Reactor once again, and Lyner and his friends went to investigate after they heard that Lyner's father, Leard, had gone there with an squad and hadn't returned yet. Once there, they had the unpleasant surprise of Shurelia announcing that the world would undergo a radical change, beginning with the annihilation of humans for the creation of a Reyvateil-only paradise. Lyner then stepped in an confronted Shurelia, who merely used a Guardian to bide for time while she surrounded Leard with a energy field, and after announcing she would imprison him in the Prism Garden for knowing Special Level-A classified information, she teleported both Lead and herself out from the Reactor. Krusche then thought that something must have happened to Misha, and Jack advised to rush to the Crescent Chronicle to check on her.
After the Download of the Purger was finished, Lyner took Misha and the rest of the party to the main chamber of the Reactor while Aurica waited safely in Platina. Once there, they saw Shurelia and Ayatane making a desperate last stand against the ELMA-DS, so Lyner rushed into the scene to help while Misha began singing the Purger in order to allow the party to fight against the virus without any problems. However, once the battle ended, Misha suddenly stopped singing and fell unconscious, which forced everyone to go back to Platina to check her condition.
After the battle finally ended, Shurelia opened up the warp gate that was located further inside the Reactor, which led to the Frozen Eye, finally opening up the path between the Upper and Lower Worlds for the first time in centuries, which allowed both Radolf's group and the party searching for Misha's lost song to return to the Wings of Horus to carry out their own duties.
Aside of this, the only appearance of the Symphonic Reactor in Misha's Route is when Misha begins singing Chronicle Key, in which shows Radolf and Ayatane fighting against Falss while Aurica is released from Mir's control.
A few months later, Lyner, Leard and Aurica/Misha went for a short walk to the main room of the Reactor, in which Leard briefed both of them about Kyle Clancy: he used to be his best friend, and like Leard himself, was pretty close to Shurelia. The three of them were called the Three Magi, and Shurelia had bestowed to each of them one special Hymn Crystal. However, Kyle committed a great crime by trying to revive Mir, and was banished from Platina by Shurelia herself. Later on, he returned to the Reactor again with the purpose of reviving Mir, but was caught by the Knights of Elemia and jumped off the main platform, apparently committing suicide, which led to everyone to presume him as dead and unable to notice that Bishop Falss and him were the same person, thus leading to the invasion of Platina. With this, Leard also explained that one of these crystals was the Hymn Crystal Re-Nation, which would allow the reactivation of the Tower, but since Kyle had taken it with him and hidden it away, they didn't know where it could be at the moment.
Although the Symphonic Reactor is rather large, there are a few areas that can't be explored during the first two Phases. Luckily, random encounters only happen here during short periods of time, and are eliminated completely in Phase 3. The Reactor is also the place where the stairs that lead to the highest section of the Tower, the Rinkernator, begin.
- Bit Ball v2 (appears in Blue areas)
- Electric Guarder (appears in Red areas)
- Wind Guarder (appears in Red and Blue areas)
- Mother Bit (appears in Green and Blue areas)
- Type 28 (appears in Red and Green areas)
- Melchior (appears in Green areas)
- Type 1025 (appears in Red areas)
During the Platina Invasion (Aurica's Route only)
- Armed Guard (appears in Red and Green areas)
- Type III (appears in Red areas)
- Order Knight (appears in Blue areas)
- Order Guard (appears in Blue areas)
During Shurelia's Possession by Mir
- Bit Ball v2 (appears in all areas)
- Wind Guarder (appears in all areas)
- Mother Bit (appears in all areas)
- Air Fort One (appears in all areas)
- Something I noticed at the Altar of Apostles (appears after clearing Shurelia's Lv. 1 Cosmosphere and disappears after clearing her Lv. 2 Cosmosphere)