Twin Blood is an alternate version of Blade and Evil's first battle, with drastically different character and mecha designs from the rest of the series. Blade/D-Boy does not need Pegas to transform and the armor more closely resembles the Radam humanoids from Tekkaman Blade II.
Watch Uchuu no Kishi Tekkaman Blade: TWIN BLOOD episode 1 online — subbed and dubbed, with automatic AniList / MyAnimeList progress sync.