A side story taking place somewhere before the second half of the series, prior to Daba acquiring the L-Gaim Mk-II. Daba's comrade Leccee is captured by Poseidal's forces, and Daba and his rebels attempt to save her.
Watch Juusenki L-Gaim III: Full Metal Soldier episode 1 online — subbed and dubbed, with automatic AniList / MyAnimeList progress sync.