Sony Corp recently announced that it plans on entering the e-book market in Japan as soon as possible, by opening an online bookstore with 20,000 titles. Most of them will be Japanese and this service will kick off in time for the Christmas season, according to Reuters. There’s also a gadget associated with this e-book store, an e-reader with a 5 inch display.

The product will retail starting December 10, for $240 and it’ll also be available in a 6 inch version. Sony wants to sell 300,000 readers in the first year and reach a 50% market share locally by 2012. Back in 2007 Sony and Panasonic retired from the e-reader biz, because of the lack of book titles and now Sony is back to make a better impression.

Among the rivals of the new device we must mention the iPad and Sharp’s Galapagos units. For now, there’s no Kindle in Japan, but that would kind of kill Sony’s newcomer…