Ultraman Saga

Taking place 15 years after Shin Asuka (Ultraman Dyna) disappeared through a black hole at the series's ending, Earth has since then set up a space station on Mars in Asuka's honor and memory. The space station is then attacked by a few Granspheres, only for the invaders to quickly be fended off by a young defense team pilot named Taiga. Shortly after recklessly pursuing the Granspheres, Taiga is trapped (along with a few other Granspheres) inside of a Fortress-like Ship of an invading alien force, that quickly disappears.