In the online RPG "Union" was Subaru, a party of grade school players. One day, two of its members Asahi and Haruto exchanged a promise and a ring. But Asahi sacrificed herself to protect Haruto and also died in real life. The game then suspended operations and the members of Subaru went their separate ways. Six years later, Haruto logs into the newly released "Re'Union" and reunites with Asahi.

Haruto is shocked by Asahi's sudden appearance in Re'Union six years after her death. Asahi acts as if nothing has happened, although she's unable to log out from the game. Players have noticed Asahi's existence and try to take her, but the former Subaru member Takanori appears. He had become the leader of the elite guild Illuminati. Asahi suggests reassembling Subaru, but...

Having reunited with Asahi in Re'Union, Satsuki asks Asahi to stay away from Haruto for his sake. However, Satsuki realizes that she was jealous of Asahi after witnessing her share a moment with Haruto six years ago, and vows to herself that she won't lose this time. In order to find out Asahi's identity, the three of them head to the dungeon where Asahi got her game over all those years ago.

The three Subaru members defeat the boss Purgatorio responsible for Asahi's game over. Upon his defeat, they see mysterious images inside their heads, and Asahi suspects they are her memories. They set out to find the remaining Subaru members when they are surrounded by members of the elite Southern Cross guild who are after Asahi. They're soon joined by a different guild called the Brill Society.

After telling Haruto that he didn't have the right to protect Asahi, Takanori used his Divine Sense to teleport Haruto and himself to the Monochrome world. Takanori and Haruto butt heads, but Satsuki manages to intervene before it gets too far. They search for one of the former Subaru members Clive, when Takanori reappears to try to take Asahi away with the help of two major elite guilds.

The elite guilds Southern Cross and the Brill Society capture Asahi after Takanori falls for their ruse. In order to save Asahi, Haruto goes up against thousands of enemies alone, but ends up outnumbered until Satsuki and Takanori come to his aid. The three of them finally reach Asahi, only to discover that Angelus has taken control of her spirit in order to control the Prophet Art.

Haruto hears a rumor about an unbreakable sword thrust into the bottom of the sea, and heads out to sea on Captain Alwida's ship. Haruto finds his old pal Pleiades at the bottom of the sea. However, when he tries to pull it out, a huge snake monster named Aegir appears. Meanwhile, Takanori meets up with Haruto and Satsuki in the real world and tells them what he's discovered about Asahi's secret.

Haruto se despierta con el sonido de un EKG pitido para encontrar a Asahi parado sobre él. "Me sorprendería si fuera tú también. Has estado dormido durante seis años", dice Asahi, que vino con Satsuki y Takanori a visitarlo. Asahi explica que Haruto tuvo un juego cuando protegió a Nozomi de Purgatorio. Sin embargo, Haruto no está satisfecho con la explicación y les pregunta sobre Re'Union.

En Re'Union, Haruto retoma la posesión de Pléyades, que posee el poder de los miembros de Subaru. Clive recibió una solicitud de ayuda de Elicia, y le dice a todos que Elicia dice que para evitar que Gnosis despierte a Asahi, es necesario despertar a todos los miembros de Subaru. Mientras tanto, Haruto y Satsuki se reúnen con Nozomi en el mundo real, y le piden que inicie sesión en Re'Union nuevamente.

Saki, quien fue influenciado por Yang Xi, parecía haber arreglado un sentimiento, "porque no fue que terminé siendo un amigo de la infancia por separado" para Yangosang, lo que parecía poco probable. Su método llama a esas dos personas. Es una realidad, rara desapareció de repente. Con la ayuda de Clive, sabiendo que lo raro es iniciar sesión en Reunion, Yang Xi se dirige a un lugar donde parece ser raro. Sin embargo, hubo escándalos raros que presenciaron la danza de usted y Dazuki, que se incorporó en gnóstico.

El accidente atacó repentinamente a las tres personas de Yang Xiang, Sakiyuki y Kimi que se unieron en el mundo real hacia la recuperación. Un misterioso hombre de pie junto a las tres personas desapareció dejando un significado significativo "para cambiar el futuro de la desesperación, el poder de seleccionar el mundo ideal es necesario". Tres personas que recordaban las palabras de Elysia y estaban convencidas de que la sensación de Reunion se invocaba en el mundo real se reunieron en el pellejo al pensar en Asahi, pero el lugar también fue asaltado por alguien. Apareció antes de que Subaru intentara escapar de emergencia ...