To find a specific walkthrough or "Capture Guide" (攻略 - Koryaku ), search for the game's title rather than just the RJ code: Go to the website. Paste RJ439552 into their search bar to get the full title.
Because this code could refer to a few different types of content, 1. Extracting the File RJ439552.rar
Since the file ends in , you’ll need a specific utility to open it: Software : Use 7-Zip (free/open-source) or WinRAR . To find a specific walkthrough or "Capture Guide"
It looks like you’re looking for help with , which is a product code (likely from DLsite) for a specific Japanese indie game or ASMR/voice work. RJ439552.rar