Manga Club is a site that posts officially licensed manga free with ads. But we're not telling you about it because free manga is great; they recently added the ability to easily switch between Japanese and English with the press of a button!
Now you can read free manga without needing to choose whether to buy Japanese, English, or both, if you want to use them to study. Now, if you aren't sure what a sentence means in English, you can switch back to see how it was translated. And for a site that's only existed for about two months, there's already tons of manga to choose from.
A quick warning though: there's a lot of adult content on this site and some of the ads reflect this. Adults only for the ones that say so, okay? I'll trust you.