The official website for the Sword Art Online: Extra Edition special announced on Tuesday that Eir Aoi will be returning to perform the special's theme "Niji no Oto" (The Sound of the Rainbow). Aoi performed the second opening theme "Innocence" for the Sword Art Online television series. She also provided the opening theme song "Sirius" for Kill la Kill , as well as themes for Gundam Age and Fate/Zero . She performed with fellow Sword Art Online theme singer Luna Haruna at Seattle's Sakura-Con convention in April.

The single for "Niji no Oto" will go on sale in Japan on January 1.

The special will stream worldwide on January 1 on Crunchyroll and Daisuki for English-speaking countries, Mexico, and Central and South America, immediately following its Japanese premiere. The special will stream in Korea on the Aniplus cable channel; in China on the LeTV streaming site; and in France on the streaming site Wakanim. Daisuki will also stream the special in Singapore, Malaysia, the Philippines, Indonesia, German-speaking countries, Italian-speaking countries, Russian-speaking countries, India, and the Middle East.

The special will premiere on Tokyo MX TV, BS11, and Niconico in Japan on December 31 at 10:00 p.m.

Aniplex describes the story:

Kirito and the others decide to go on an underwater quest within the world of ALO to grant Yui her wish to see a whale. As they all prepare for the quest, they face a shocking revelation... Leafa, or Suguha is afraid of water. So, Asuna and the other female members decide to teach Suguha how to swim at a pool in the real world. Meanwhile, Kirito was meeting somebody…

Original light novelist Reki Kawahara took part in the writing of the two-hour special. Tomohiko Ito is returning to direct at A-1 Pictures. The original light novel series' illustrator abec gave the characters a full makeover, and character designer Shingo Adachi is again adapting abec's art for anime. The cast is also returning from the television anime.

[Via Yaraon!]