I have recently been looking for websites where I can read manga in Japanese for free (legally), and I have managed to find quite a few! Manga is great for reading practice because the pictures can really help give you additional context about what is happening in the story. If you live in Japan, its pretty easy to find cheap manga all over the place, but for people living elsewhere, it has traditionally been both difficult to get and expensive. So knowing that there are so many online sources now is fantastic!
Some of the manga websites below will let you read titles in their entirity for free, and some will only let you read a few chapters for free, and encourage you to either purchase the rest or subscribe to their service. I have not subscribed to any of these services, so I’m not sure what difficulties you might face if trying to do so outside of Japan. However, there are so many different titles available, there is enough free content to last you for ages!
Featuring titles from Kadokawa publishing, you can find some famous classics here, such as Evangelion and Lucky Star, as well as the often-recommended manga for Japanese beginners, Yotsubato! There are typically several free chapters available for each manga, including the first few chapters and the latest few chapters.
I think almost everyone knows of Shonen Jump, due to their mega hits like Dragon Ball and One Piece. It looks like they make certain titles available for free in their entirity on certain days of the week.
Pixiv features a lot of works from amateur artists, but it looks like they also carry titles that were published in popular magazines as well. Many of the titles here only feature a few chapters for free, but I have seen some titles that have every chapter available!
S-Manga is run by Shueisha publishing, which is the parent company of Shonen Jump, so you can find many Jump titles here in addition to others. For each volume or book of a series, you can typically read the first chapter online for free.
Formerly known as J-comi, according to Wikipedia, this site was created to make out-of-print manga available online. You can read titles in their entirity for free. It includes some classics like Love Hina, but it looks like a lot of the most popular items on here are erotic titles.
They want you to buy the full books, but select titles will let you read several entire volumes for free! If you just want to buy books in electronic form, it seems that you can find almost any popular title on here.
I think the most interesting parts of this site are the Twitter 4-koma and the 4Pages sections. These are particularly nice for beginners because they are so short, so its much easier to read a bit whenever you get some free time. The Twitter 4-koma section has several manga where each chapter consists of just 4 panels. There are links to allow you to go back and read each one from the very beginning. The 4pages section is similar, but each chapter is 4 pages long, and they all seem to be in full color, which is nice.
Are there any other good sites that I missed? Let me know!