Honestly, I watched the whole show and the movie in the original, and better Japanese. The sex is mentioned between Renton and Eureka (since Eureka is an alien that looks human, some of the characters wondered if she could have sex), and Talho gets pregnant later in the series.But, the whole show is based around the story and Renton trying to win over Eureka and save her than anything else. Besides mild flirting, it's violence and massive death from explosions and alien attacks. The story is complex and requires an older viewer to understand, and even that isn't saying that person won't rewatch the ending or the whole show. Save this for older kids unless you want a kid watching people getting eaten by giant aliens or shot in the head by evil little children taken in by the main antagonist.

Eureka Seven is one of the best shows that was ever played on Adult Swim. Some innuendo, violence with some blood. I think 8+ can handle it, but most parents are probably gonna say higher. I was 11 when I first watched it.