The developers, LIGHT’s, sell Axanael through Japanese digital storefronts. The primary official source is or Melonbooks DL . However, note that these sites require a Japanese IP address or a VPN to purchase, and the game is entirely in Japanese.
Look for (アザナエル). You'll see a link like: axanael_v***.zip (*** = version number, e.g., v1_10.zip )
Click to download the ZIP file (~300–400 MB).
Cost: Approximately 3,000–4,000 JPY (Roughly $20–$30 USD) Pros: Safe, virus-free, supports the creators, automatic updates. Cons: Requires a Japanese payment method (or a VPN + foreign credit card), region locks.