Files ending in .rar from unofficial sources can carry security risks. According to Whaleco Inc. v. Offidocs Group , third-party app versions can sometimes contain malicious code intended to compromise devices or steal personal information.

: Some users use the term when looking for physical notebooks or logs to track their progress in the game or to mimic the "diary" aspect of the title.

: The game involves interacting with a character who has a traumatic past; "paper" can occasionally refer to in-game documents, diary entries, or narrative items you interact with during gameplay.

The file you mentioned, Nais_Training_Diary_Uncen.rar , is a compressed archive containing an "uncensored" version of the game. In this context, "" likely refers to:

: Scanned documents or text files included in the archive that explain how to play, unlock scenes, or achieve specific endings.

Training diary - Recording, monitoring and evaluating performance ... - BBC

" Nai’s Training Diary " is a simulation game, typically available as an APK for Android, that belongs to a genre of visual novels similar to Teaching Feeling .