Yuki Yuna and Madoka Magica are relatively light on the fan service - at least, nobody trips and falls and head-butts Madoka's sternum (not enough marshmallow for hell, there.). Both also have plots that end without excessive filler, though Yuki Yuna is a Hero does have a few slice-of-life episodes, they're all relevant to... well, spoilers. And none of the characters are high-school! They're middle school.
Both do have some fan service though. It's pretty much a given in anime or, really, TV in general. Togou's (Yuki Yuna is a Hero) transformation sequence does a rather unnecessary close-up on her chest, and Madoka Magica's Puella outfits can get a bit more racy than strictly necessary, but neither really have it as a focus.
The thing is, in Japan, sex sells. A lot. A lot a lot a lot. And Japan is very adam smith about how they do business, so what happens is the marketplace is saturated with fanservicy crap all the time because that's what sells the most copies.
Or, turn to live action TV. Liar Game doesn't have any fan service at all, unless you count Nao being adorable or are the type of person who gets off to outsmarting the other pretty-boy and then slowly explaining your victory using some sort of board game metaphor thingy that doesn't exist (God, I know I do. Akiyama-sensei is so freakin' cool).