Limited boxed editions exist. Check or Mandarake using the Japanese title: 猟獄島 ～極痴恋愛～ . The physical DVD includes the raw game plus a bonus disc with kyokuchi sound dramas.
Since you are looking for "raw" (original Japanese) versions, these are typically hosted on official Japanese digital platforms. Reading the raws allows for an unfiltered look at Shinzaki's original dialogue and pacing before any localization changes. rengokujima ~kyokuchi renai~ raw
: Look for platforms that specialize in manga and anime, such as Crunchyroll, Funimation, or raw manga sites (be cautious with raw sites as they may not always be legal). Limited boxed editions exist
This site typically hosts the most recent chapters and select early chapters for free viewing. Since you are looking for "raw" (original Japanese)
Given the title “Purgatory Island,” there is a high probability the game contains content that violates most Western content distribution policies:
Google Play
App Store