Also on amazon.co.jp! Thanks for the heads up!
To anyone else planning to read in that time frame, I wouldn’t worry too much about finishing them all. The same volumes were free to read back in May, so I reckon it’ll probably keep happening semi regularly.
Last time I read until volume 18 (thanks, natively, for keeping my records haha), so I’ll simply quickly skim the last chapter for context and continue from 19. 
