Two more to make note of:
The MangaUpdate description of Pa, which should be spelled "P.A." and stands for "Private Actress," make it sound pretty cheesy: high school girl moonlights as a "private actress," taking on roles in people's lives (usually as a daughter, but sometimes a lover) rather than on (sound)stage. I tried it anyway and was pleasantly surprised. As a seinen premise, I'd run away from the skeeviness faster than a bandicoot, but it turns out to be an early-90s josei series by the mangaka of Super Girl (aka. Hime 100%) and Alpine Rose. It's not brilliant, but the stories and art are good (if old-school) and the plots emotionally complex. Unfortunately, the scanlators dropped it after three volumes. Give it a whirl.
Platinum Garden is an odd duck: it starts out as Yet Another(tm) teenage-girl-sold-into-arranged-marriage-to-pay-off-debt story, but with hints of something more, which seems to show up when it develops into a scrappy-middle-class-kid-in-snobbish-high-school story. But no, that's a red herring, as by the end of the third volume it morphs into what I can only describe as a sideways Fruits Basket rip-off. Yes, really. If this bizarre combination of elements intrigues you, you may like it. If you're looking for the shoujo smut the initial premise seems to promise, you're out of luck here.