Supercharge Your Memory! is a book Homura stole in Loop 2 and purchased in Loop 3 to attempt to improve her memory. When complete, it will unlock the SCREENSHOT feature in her MENU > DISPLAY menu section.
A 400-page book about memory. (Upon completion, unlocks [SCREENSHOT] option in Homura’s [MENU > DISPLAY], which gives Homura ten slots to record information in and can be immediately called up for reference.)