There are no shortage of anime which put a mecha genre spin on the “modern-day character ends up in fantasy/alien world” (isekai) theme. From Aura Battler Dunbine through arguably series like Orguss into ones like Magic Knight Rayearth or The Visions of Escaflowne it has strong precedent, and it is a genre that brings a few additional interesting themes to the traditional science-fiction and fantasy ones. I am personally very interested in stories of culture shock, or outsiders to a society trying to fit in; it is for this reason I was quite disappointed in the TV adaptation of Crest of the Stars because it hinted at being a story of a human living as the ward of aliens and learning their culture, and then did not really deliver so much on that. One could almost consider, actually, a story like Crest of the Stars as the pure science-fiction equivalent to the isekai story – a human living among aliens.
Magic Knight Rayearth represents acclaimed studio CLAMP’s most recognised entry into the science-fiction genre, creating a magical super-robot series in the vein of Aura Battler Dunbine, but with aspects of the fighting magical girl genre popularised by Sailor Moon. Across its two series it gradually moved away from the fantasy adventure aspects and more into the super-robot field, eventually becoming a very standard robot adventure series with themed villains of different specialties and later-revealed overlord and rival figures in Debonair and Nova. Coming as it did at a time when animé producers were seeking to attract new audiences in established genres (around the same time as other mecha series for female audiences, such as Gundam Wing and Brave Command Dagwon, were airing), its first series provided a novel approach to super-robot animé that holds up well today.