W Change is a pretty good Yakuza fighting/political conspiracy manga and a pretty good ecchi romance manga rolled into one. If you're just looking for one or the other, there are probably better manga out there--but all in all, W Change is more than the sum of it's parts, and is good enough to be worth a read if that combination strikes you as interesting.
The plot centers on Maki, a high school girl and heiress to a Yakuza clan. Her dream is to leave the Yakuza and be a normal housewife, except that her repressed anger comes out increasingly often as a "black"
personality that embraces the Yakuza and is an unstoppable fighting force.
Maki has growing feelings for Fukama, a childhood friend and the heir to a rival Yakuza clan (though the two groups have been at peace for awhile). He also wants to get out, though he has reluctantly (at least for now) accepted his role as heir.
Complicating all of that is a third, at first mysterious, Yakuza clan that is trying to move in and take over all of their territory, for some nefarious purpose.
It's all a little absurd, of course, but that's to be expected given the genre. Still, given the premise, the plot and character development are all handled well. And the mangaka never allows things to get overly dark. Sure, there is violence and murder and plenty of panty shots, but the torture, gore, and sexual assault are all kept fairly minimal.
The art and action sequences are all done pretty well. I liked the character models a lot, and the action sequences are all pretty good, although occasionally they can be hard to follow.
In short, if you don't mind the sometimes awkward blending of sappy romance, shounen action sequences, and convoluted plot explanations, this is really quite an enjoyable manga.