Man, within the first 2 pages we already have proof why this manga rules; dude says "We gonna fuck!" she says "Wait that's a lil fast" he says "Well we're going to right?" and she says "Well yeah, eventually we will." And even then, mom says use protection, and she admits that she doesn't know if they'll marry but she's more than willing to try to make their relationship work.
Like not pussyfooting around it, not pretending every Japanese teenager is some 17th Century Catholic nun. Shit's so refreshing.
Sure maybe I'm over-rating this manga, but it's also because I'm giving it a lot of leeway for doing some very big things very very differently than 99% of manga.