Gunslinger Stratos The Animation: Kikan/Kaze no Yukue
Genres: Action, Sci-Fi
Type: ONA, Episodes: 1
Aired: Jun 20, 2015
Studio: A-1 Pictures
Source: Unknown
Rating: PG-13 - Teens 13 or older
Synopsis:
Web version of episode 12, aired on Niconico and Daisuki. Features alternative ending.

Because the Frontier S Tooru cannot believe the eradication of the Timekeepers leads to true salvation for both futures, he challenges the 17th Tooru for one last battle. The ultimate showdown begins, with the two futures at stake.

(Source: AniDB)