Rei Takashima is a doctor and scientist of Deadman Wonderland. Her main duties are to research the various deadmen that are imprisoned there.
Not much is known about Rei's past before she became a worker at Deadman Wonderland. She was born in Japan and is probably one of many survivors of the Great Tokyo Earthquake from ten years ago. However, her skills as a doctor and as a scientist attracted Tamaki Tsunenaga. She became an employee of the G-Ward as she specialized in studying the various body parts that various Deadmen gave up for the advances in science. She works exclusively with Tamaki in Deadman Wonderland with their experiments in the prison.