Gravion is a popular anime franchise by studio Gonzo which combined mecha stories with a focus on cute, sexy girls and moe. The first series aired in 2002, and the second, Gravion Zwei, in 2004. It’s trashy Gonzo at it’s peak and marketed its girls hard for the otaku crowd, giving plenty of sexiness over the years.
Just look at some of these promo and Megami pinup illustrations!
Unlike a lot of other shows of this ilk though, Gravion has some other things going for it that make it worth watching such as a self-parodying tone, and 80s-style mecha animation. The amount of fanservice in the show is just enough that you wouldn’t class it as ecchi but it’s still got the goods!