When I was in japan, there were ads for loli games and mangas in Akiba like for any other kind, they don't "hide" them more than any 18+ stuff. I'd say main difference between japan and western countries is mostly that save from a few "hardcore" otakus (the kind who's all about marrying waifus for real and so on), they know that it's just fiction and that enjoying fiction and drawing is not the same as enjoying the actual real thing.
Interestingly, western people manages to do that dissociation when it's about killing, but whenever things involves children in a somewhat sexualized situation, people goes berserk, sometimes from pretty much nothing (as Nezchan said, the only somewhat sexualized thing that happened so far was the teaser with Yuzumori sniffing Mimika's chest) and yet, people react like Mimika did all sort of unthinkable things to Yuzumori...
There's some sort of weird gap in mentality... I remember when skyrim got released, an awful lot of people complained about the fact you couldn't kill the child character in there and after a few mods got out, you could see in several place, including the wikis, people discussing in great detail how they kept killing the childs in "inventive" ways, all in a cheerful, casual way and nobody ever went "you guys are sick in the head !"
It's all fiction, involving fictional characters. If that still disturbs you, it's fine, that's your own sensitivity and we all have our own, but don't go on a crusade like that for something so minor as this manga. That's pretty much over reacting and patronizing. Just stop reading, it's not like people will force you to keep reading this manga or any other.