DEEP BRAIN is an adventure game featuring a female protagonist named "Nana". Players take on the role of Nana as they search for clues in a mysterious laboratory, navigate through its complex structure, and uncover the secrets behind the world's drastic changes in order to find a way to escape. The laboratory is teeming with malevolent monsters who have their eyes set on Nana, and making careless decisions could lead to her being violated without mercy.