Mochi characters that actually have sex?

Not to mention that they smash cut straight from "oh well, let's go on a date, anyway" to "how the Hell did we end up in bed?!" If these girls were this ready to get into the sack with one another, wouldn't they have picked up on some of this sexual tension while, you know, growing up together?!

Well, now it seems less abrupt with the "previous" chapters in mind, doesn't it?