While Go Nagai’s Cutey Honey certainly popularized the sexy girl archetype and a certain strand of fanservice, it certainly wasn’t the first anime series to feature sexiness. As far as I can tell, this is! Fushiga na Melmo aired in 1971 and is the story of a young girl who is given magic pills that can change her or others’ age and various other things. Her adventures throughout have morals about growing up and all the fun that goes with it.
When she uses the pills to age-up, the series accentuates this with a certain air of sexiness which is why I’d call it the first case of intended fanservice. There were panty shots and nudity before this but not sexual in nature.
Her first-age up is marked by a classic panty-shot and embarrassment! Also quite a nice ass for 1971 art quality..
And here it is! As far as I can find, the first female nipples in an anime bathing scene! Sadly it’s not repeated for the rest of the show.
It also features plenty of panty-shots of the young girls in Tezuka style.
