Recettear is basically what you would get if you brought Charles Dickens back from the dead, dosed him on antidepressants until he was drooling, and then set him down to make a computer game.
The plot is that a girl (you) has been orphaned, and her parents took out some giant debts. Unless you can figure out how to pay those debts, they're going to kick your♥♥♥♥♥out onto the street, and you will be forced to live out of a cardboard box. They have sent the world's tiniest loan officer in to help ensure that the company gets its money.
To do this you have to successfully run a business, either by buying products cheap and selling them at higher prices, or by convincing hapless adventurers to go recover items for you that you can then hawk. The dungeons are full of some of the happiest looking monsters around.
It actually works quite well as a pretty solid little hybrid dungeon crawl/shop management game, and the cute elements really help undercut what would otherwise be a pretty dark theme. Has a fair bit of replayability, and is worth picking up.