This is official JAST version of “Saya no Uta” game. If you’re looking for fantranslated version then use this link instead.
Enter the world of Sakisaka Fuminori, a medical student who receives experimental brain surgery after a traumatic accident. He survives, but is left with warped senses that perceive the world around him as a place of terror. Into this world comes Saya, a girl who is the only thing that now seems pure. With a scenario that stands as one of the first defining works of Madoka Magica and Fate/Zero creator Urobuchi Gen, nothing is as it seems — can you find away to escape the nightmare that surrounds you? A seminal work of horror and occult fiction in the visual novel medium.