The Nihon Ki-in has two good series with textbooks (mostly graded problems illustrating various concepts, so one can use them even without knowing Japanese). They are not as comprehensive as the Speed Baduk series but they have more problems related to direction of play and strategy than the Speed Baduk. They are better conceived than the old 1970s series Graded Go Problems for beginners and more comprehensive than the Chinese textbooks used by Nie Weiping Go Academy (and unlike the latter they provide the answers to all problems). The books can also be ordered over seas through Japanese Amazon
The first series has 12 booklets and is for absolute beginnners to SDK kyu:
https://www.amazon.co.jp/-/en/dp/4818206385
https://www.amazon.co.jp/-/en/dp/4818206393
https://www.amazon.co.jp/-/en/dp/4818206407
https://www.amazon.co.jp/-/en/dp/4818206415
https://www.amazon.co.jp/-/en/dp/4818206423
https://www.amazon.co.jp/-/en/dp/4818206431
https://www.amazon.co.jp/-/en/dp/481820644X
https://www.amazon.co.jp/-/en/dp/4818206458
https://www.amazon.co.jp/-/en/dp/4818206466
https://www.amazon.co.jp/-/en/dp/4818206474
https://www.amazon.co.jp/-/en/dp/4818206482
https://www.amazon.co.jp/-/en/dp/4818206490
The second series has five books and is DDK to 1 dan:
https://www.amazon.co.jp/-/en/dp/4818205109
https://www.amazon.co.jp/-/en/dp/4818205125
https://www.amazon.co.jp/-/en/dp/4818205117
https://www.amazon.co.jp/-/en/dp/4818205338
https://www.amazon.co.jp/-/en/dp/4818205435
It should be noted that these series seem to be directed at adults (judging from the Amazon reviews middle age people taking up Go as a hobby) since the Nihon Ki-in has other textbooks directed at children.