So, I've watched Imouto Jiru and Another lady innocent.
Both look like rather generic hentai, though the former had the cute nude apron moment, and latter had that daughter hug while sex moment and it could probably get better in the later episodes, but unfortunately there isn't any.

Also I've stumbled onto the manga Mujaki na Rakuen. It's a comedy that derives its fun from children constantly getting into some sexy situations without realizing how sexy those situations are (except for the protagonist who is actually a 25 years old guy who happened to time leap into his childhood).
For example, a girl and her father sit on a bench in the park and chat. The father happens to drop a bottle of water onto his daughter so that it wets her panties. She lets him pull off her panties just right there. Later she climbs a whatever that construction of tubes on playground where children climb is called without care that the protagonist can see from below her lack of panties. Later she joins the protagonist in the bathroom without seeing anything wrong with it.
Though I think it goes a bit too far with mostly each episode ending in the protagonist somehow cumming (usually as a result of accidental touches by girls) which he also tries to hide which results in him having such an expression on his face that you can't say if he came or had his balls crushed.
And it also gets somewhat repetitive after a while.
It's not 100% ideal, as the protagonist being aware of sexuality and embarrassed by it goes against the casual atmosphere, and also it keeps staying on that unsatisfying edge where it goes almost to actual sex, but actually it doesn't. I mean, if it's about innocence, I'd go with either they can all casually be naked and hug and wrestle and whatever without it giving anyone any sexual thoughts (the reader is allowed to have such thoughts and the author is allowed to frame shots to make the reader have them, but the characters are not) OR like in my "Innocence" story where they can all casually have all kinds of sex with each other, but still not have any "sexual" thoughts, if it makes any sense, like it's just a fun game, but it wouldn't occur to them to associate it with lust, filth or even relationships. Also if you're interested in the latter, take a look at Aogami's drawings if you can find them (see the other thread I've just started where I wonder how to find that artists' new works).

There was something else I wanted to say on the topic...
Ah! The Flip Flappers. I stumbled onto this AMV for it ( https://www.youtube.com/watch?v=d3Iv1gscw5M ) and can now see how it is related to the topic. I wonder though if I should wait for Blu-Ray version? Usually BD versions have censorship removed from such titles, but in this one it seem there isn't any censorship to begin with. On the other hand, sometimes BD versions also have improved visuals, and for something this colorful it wouldn't do it justice not to watch it in its best form.