Blood is a bodily fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. When it reaches the lungs, gas exchange occurs when carbon dioxide is diffused out of the blood into the pulmonary alveoli and oxygen is diffused into the blood. This oxygenated blood is pumped to the left hand side of the heart in the pulmonary vein and enters the left atrium. From here it passes through the mitral valve, through the ventricle and taken all around the body by the aorta. Blood contains antibodies, nutrients, oxygen and much more to help the body work.

Blood+, pronounced as "Blood Plus", is an anime series produced by Production I.G and Aniplex and directed by Junichi Fujisaku. The series premiered in Japan on Sony's anime satellite channel, Animax, as well as on terrestrial networks such as MBS, TBS, and RKB on October 8, 2005. The final episode aired on September 23, 2006. Blood+ is licensed for international distribution in several regions through Sony Pictures' international arm, Sony Pictures Television International (SPTI).