Oh, that's a lot of everything. Let's see...

> Astarotte no Omocha
I remember starting watching the anime, then I dropped it, don't really remember why... from what I remember there was a pantyless girl who was just what I'm looking for, but the rest wasn't any good...
I've just read the first chapter of the manga and it seems to be more open about her pantylessness than the anime. I guess I can give manga a try then.

> Kodomo No Jikan
> Kanokon
> KissXSis
> Queen's Blade
It seems these all have both anime and manga, so I wonder if the anime for any of them worth watching or I should go straight to the manga?

> Touhou anime series
Is there such a thing? I've always though there are only games and Google seems to concur with me.

> Pokemon beach episode.
Since you didn't specify which it is, I googled "Pokemon beach episode" and it gave me
> Pokémon Episode - 18 "Beauty and the Beach"
and it doesn't seem to have anything any other beach episode of any other anime doesn't have.
I think I've already mentioned that beach episodes and bikinis don't count because you can see them in every other anime anyway?

> Imouto Jiru
> The Story of 15 Girls adrift
I'll look into these.

BTW I've also looked into naturist films suggested above...
...wait, where was that?
I guess it wasn't really a suggestion, just mention of nudism?
Anyway, I looked into it and they are just videos of people doing some day to day activities in the nude.
Now you can say that this is what I asked for, but watching ordinary people lead ordinary lives is still boring even if they're nude. In fiction even if it's a slice of life genre, it brings up most fun moments of everyday life, not only that, but it takes effort to give personality to the characters so that one can relate to them.
Also those films come in all kind of languages without translation.
Even the zenra genre is closer to what I'm looking for, because at least some deliberate though was put into it, but while I can enjoy it as a form of porn, I've already mentioned how it isn't what I'm looking for in this post.


Thanks for all the suggestions!