Cordial Chords

Cordial Chords (コーディアル・コード) is an extra story written by the author of the Sword Art Online light novel series, Kawahara Reki. It was released with the Japanese Limited Edition Blu-Rays and DVDs of Ordinal Scale, and is a sequel to the events of Hopeful Chant and Ordinal Scale.

Prologue
On May 7, 2026, Kirigaya Kazuto and Yuuki Asuna were spending their lunch break in a difficult-to-reach green zone their school's campus. With his girlfriend sleeping on his lap, the boy gently caressed her hair as he contemplated on how the sensation of hair, among other things, was handled in games. Having suddenly awoken in the midst of his musings and discovered where she was lying, Asuna attempted to rise to her feet due to feeling embarrassed. However, she was stopped by Kazuto, who urged her to sleep a little longer, arguing that they still had twenty minutes of their break left, while Doctor Kurahashi had stated that sleep would accelerate her recovery from the memory scan conducted on her. Despite showing some resistance, the girl once again lay her head on Kazuto's lap, before returning to sleep.

Part 1
Kazuto recalled the scepticism that the Augma was met with when it was announced, due to being developed by a company that had specialised in social networking games and video streaming services, rather than being a manufacturing company. For most people, these doubts were completely eliminated with the release of Ordinal Scale, a game that had attained tremendous popularity upon release due to a variety of reasons. However, Kazuto remained suspicious, as the technology employed for the Augma to allow it to send visual, auditory, and limited tactile signals into the user's brain was far too advanced for company that had just entered the industry. Although the announcement that the Augma's development was spearheaded by Kayaba Akihiko's mentor, Professor Shigemura Tetsuhiro, explained how the company was able to develop such advanced technology, it did not abate Kazuto's cautiousness.

Then, at the end of April, Kazuto discovered about the professor's plans to use Ordinal Scale to scan the memories of Sword Art Online (SAO) survivors in order to use their memories of his daughter, Shigemura Yuuna, to recreate her as a digital ghost. The professor was thus able to create «White Yuna», an Artificial Intelligence (AI) with his daughter's personality and limited memories, based on the language engine of An Incarnation of the Radius, the monster that was meant to serve as the final boss of Sword Art Online before it became a death game, and the collected memories. However, as the personality of the AI was too accurate, it assisted Kazuto and the others in defeating the boss in order to stop the professor's plans before it could kill a large number of SAO survivors, despite knowing that the defeat of the boss would result in the AI itself being deleted.

However, even eight days after the incident, Kazuto could not stop thinking about two things. The first was Nochizawa Eiji, Shigemura Yuuna's childhood friend who had been helping with the professor's plans. Due to the bodily injury Eiji had inflicted to the members of Fuurinkazan, Eiji had surrendered himself to the police two days after the incident and was still being detained, though he was likely to avoid prosecution due to the Fuurinkazan members not pressing charges against him. The other was YUNA (Black Yuna), the Ordinal Scale image character and Augmented Reality idol, who possessed a simpler personality than White Yuna and was still working as an idol. While Kazuto felt it unlikely to meet either of the two ever again, he believed that he would not be able to forget them so easily.

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