Just a piece of advice Shimizu-san. If you planning on spending the rest of your life, with someone, you might want to start calling her by her given name.
While I know Japan is a different culture, I still can't get my head around calling someone you're dating by their family name, especially if you get to the point you're sleeping with them. It just feels just so damn impersonal.
She did call her "Akane-san" when speaking to her father, although from what I've heard, it's generally expected to use first names+san on someone if you're talking about them with their family.
Other than that, I'll second your point about the first names. It's true that in Japan, first names are generally reserved for people who are close (although how readily people make the jump to a first-name basis depends on the series; in some series, characters might even get onto a first-name basis with people they've just met), but one would think Shimizu and Maekawa would be close enough by now.