It was originally developed as a .swf (Adobe Flash) file. Due to the end-of-life for Adobe Flash, many modern users access it through specialized emulators or archived versions on community forums. Community and Legacy

Circle Eden is well-regarded in the fan community for creating highly thematic works that capture the darker, more clinical atmosphere of Mayuri’s research institute. Discussion and support for the English version can still be found on niche communities like E-Hentai and specialized translation forums, where enthusiasts continue to preserve this piece of early 2000s fan history.

Circle Eden has carved out a reputation for a very specific aesthetic. Unlike mainstream visual novels that might focus on romance or high school drama, Circle Eden’s work—specifically the Mayuri Sama series—dives headfirst into the Clinical and the Gothic .

It looks like you're looking for the full English version of (or possibly part "5-5").

Circle Eden: Mayuri-sama no Jintai Jikkenshitsu " (translated as Mayuri-sama's Human Body Laboratory ) is an adult-oriented fan-made Flash game based on the franchise, developed by the doujin group Circle Eden

However, if you are looking to find it legally: