Sure, you might be able to read Nochi Kareshi manga online. But make sure you use legitimate sources to support the creators and avoid any legal complications.
Overall, the relationship depends on the specific adaptation. Some capture the core elements well, but there could be changes in details or plot sequencing for various reasons like medium differences or creative decisions.
Websites like KissManga or Manganelo could be good places to look. But remember, make sure the site is legitimate to avoid any potential legal issues or poor reading experiences.