I've always put off reading anything by Motomi Kyousuke because I really didn't like the art style (really wide faces, funny mouth/nose proportions, etc.), but when I finally picked this up, it made me regret not having tried it sooner. It's awesome!
The story revolves around Oikawa Ibuki, a very "manly" girl who's determined to pass herself off as girly so that she can find a guy even manlier than she is. I'm not sure why so many commenters here mentioned "solving mysteries" around the school, because that's hardly the point here. What it's really about is the situations Ibuki gets into with the school council/beads club, partly due to the strange jobs they take up and partly due to her quest for a manly boyfriend. It's a great deal of fun, but this isn't something you can expect an amazing plot from in the first place.
Considering the main story is only composed of 3 chapters and an extra, the relationship between the main leads are reasonably well-developed. Usually I wince whenever authors add extra chapters about the couple after they've gotten together (because this almost always signals contrived misunderstandings and jealous fits), but it was used really nicely here to show how well Ibuki and Takumi understand each other. There isn't much in terms of individual character growth, but again, this story is just plain hilarious and goofy. What is there definitely works, and that's enough for me. The supporting characters are mostly even crazier than Ibuki and Takumi - it would've been fun if we got to know them better. Ah, well!
The oneshot was cute, but unremarkable - romantics might be a little annoyed that it was more about the girl forgiving (and helping!) her cheating ex than her developing interest in her childhood friend. All in all, a really entertaining one-volume manga! Enjoy it as a wacky story with weird and unique characters and don't take it too seriously.