Dengeki Thanks Festival 2018: TV Anime "Sword Art Online Alternative Gun Gale Online" Premiere Set for April 7
The OP theme song "Ryusei" is performed by Eir Aoi,

And finally at the "Game no Dengeki Thanks Festival 2018 featuring Dengeki Buko" event, it was announced that the upcoming TV anime adaptation of Keiichi Sigsawa's light novel Sword Art Online Alternative Gun Gale Online is set to premiere on Tokyo MX, Tochigi TV, Gunma TV, BS11 and MBS on April 7, then on TV Aichi two days later. It will be also simultaneously streamed on internet TV for PC and smartphone, AbemaTV.
【放送日&配信日公開!】
— TVアニメ「SAO オルタナティブ ガンゲイル・オンライン」公式 (@ggo_anime) 2018年3月10日
初回放送日・配信日が決定いたしました!4月7日(土)24時より順次スタートです!CS日テレプラスでの放送とAbemaTVでの地上波同時配信も決定!
詳しくはこちら→https://t.co/Uo5pAHZf5E#ggo_anime pic.twitter.com/UXgKEOOMyj
Key visual
The spin-off series inspired by the MMOFPS "Gun Gale Online" appeared in the fifth and sixth volumes of Reki
Kawahara's Sword Art Online series has released six volumes from Dengeki Bunko since December 2014.
Novel 1st and 6th volume covers
Source: Kadokawa press release, TV anime "Sword Art Online Alternative Gun Gale Online" official Twitter
(C)2017 Keiichi Sigsawa/KADOKAWA Ascii Media Works/GGO Project