Manga in Original Japanese
Here is a list of places I buy manga online (both physical and digital books). All places deal with manga in Japanese text.
eBook Japan: Obviously, this place sells e-books. And they let you use non-Japanese credit cards. You can also subscribe to magazines so you can purchase them automatically when they are released. You have to download their app to read the books. You will accumulate points and you can use them towards future purchases. UPDATE: As of March 2019, you had to relocate to the Yahoo service which now does not let you download the app from overseas. People are angry because eBookJapan was supposed to be a service which people living overseas could use. It seems that now you need a phone number in Japan to make an account with Yahoo Japan (which you need to log in with for eBook Japan now). And the points are useless because it is now affiliated with a Yahoo service which you can’t use if you live overseas.
Amazon Japan: A good place to order Japanese manga and have them shipped overseas. It is fast and reliable although it may cost a bit. You have to make a separate Amazon Japan account but you can use your non-Japanese credit card. Note that Kindle doesn’t work for people outside of Japan so don’t bother with their ebooks.
Rakuten Books: You can buy ebooks from Rakuten (via non-Japanese credit cards) and read them in your Kobo reader app available worldwide. You can use your foreign credit card to purchase.
Honto: This place sells both e-books and actual books, but the app is only available from Japanese accounts (e.g. Apple ID with Japanese address). They often give out coupons or have sales for e-books so you can get great deals. You have to download their app to read books usually but quite a large selection can also be read on the browser. You can use non-Japanese credit cards and they will mail around the world. They have the SAL shipping option. You can accumulate points here as well.
Renta: This is where you can rent or purchase manga digitally. It’s a popular site and carries a lot of BL manga (some that are no available elsewhere). I have never purchased from here but hear their picture quality is not good. You read their books online. You can use non-Japanese credit cards.
Horin Love Books: This place specializes mostly in Boy’s Love books. They will also ship around the world and you can ask for the SAL option. This place gives out extras with some books. You can use non-Japanese credit cards. Note: as of November 2018, they only ship with the EMS method.
ComiComi Studio: This place also gives out specials with various books and specializes in Boy’s Love books as well. They ship around the world but only have the expensive EMS option. You can buy using non-Japanese credit cards.
Mandarake: You can buy used books here. You sometimes have to search often if you are looking for something rare. Prices are sometimes expensive for popular and rare items. They mail overseas and you can use non-Japanese credit cards. Website is in English but for best results search in Japanese text.
Digital Manga reading sites in English
Futekiya: Rather new, but a great place to officially read manga titles in English digitally. They license titles themselves so they have a collection of manga which you will not find elsewhere. It includes OnBlue titles (Shodensha) which you can never go wrong with. They’ve also licensed quite a few from Home-Sha, Eiwa Publishing, and Kaiousha For a small fee you get to read their entire catalogue, which is updated frequently. If you read your BL manga in English, this is a site you should surely subscribe to. The 6 month subscription is a good deal.
Renta: They have a big library of BL titles too, and carry some really popular titles that you won’t see elsewhere. This is the English version of the Japanese Renta site but have books in English. You rent/borrow or purchase the volume or chapter and is not a subscription based catalogue.
Bookwalker: A small selection of titles, old and new which you purchase by volume. Some of these are digital versions of print titles released in North America.
Manga.Club: Quite a few BL titles can be found here too! Their catalogue includes Fusion Product omegaverse titles. You have to buy tickets or coins to read the chapters. They have free content as well. You can also buy Titan’s Bride goods that were available at Manga10 in Japan for their Titan’s Bride exhibition held in 2020. This site is run by Torico which also owns Horin Love books and Manga10.
YaoiCat: This is another subscription service and they have titles similar to Manga.Club. It’s very affordable for $5 a month.