To prevent bending, just area the manga underneath a pile of other books, which will almost certainly bring about them flattening following a while. If you'd like to stay away from the backbone breaking, just watch out and really feel the book – when you're feeling the book resisting additional https://docs.google.com/spreadsheets/d/1PuM4kkw38A9TAOrirAkPhsvZQ-nPMScwCjP5I4FUBj8/edit?gid=0#gid=0