The .rar extension indicates a compressed archive, typically used for sharing high-resolution scans of the manga volumes.
The specific file mentioned, "01-03," indicates it bundles the first three volumes of the manga adaptation. Plot Summary
While these files circulate on digital sharing platforms, the series is officially licensed in English under the title "The Other World's Books Depend on the Bean Counter" and is available through legitimate digital and physical retailers. WinRAR - Page 8 - ENCODE.SU Forum
The series is a popular "Boys' Love" (BL) fantasy work centered around themes of isekai (reincarnation in another world) and corporate work culture.