The demand for the stems from convenience. While many visual novels are initially released on PC (via platforms like Steam or Itch.io), a massive portion of the fanbase prefers gaming on the go. Android devices offer the privacy and portability that desktops cannot match.
Before installing the APK, download it to your PC (if possible) and scan it using an online virus scanner like VirusTotal. If you download directly to your phone, ensure you have a reputable mobile antivirus app installed to scan the file before opening it.