Cells At Work! Is a great anime that shows life of cells working in a young, healthy body. And now, it has a spin-off in the form of Cells At Work! CODE BLACK!, which is a darker, more violent tale.
Taking place in an unhealthy body, two cells, a rookie red blood cell named AA2153 and a white blood cell named U-1196, CODE BLACK! Is not for the faint of heart or kids. While the original Cells At Work is known for having some violent action scenes (especially with the white blood cells fighting virus and killing them in gory fashion), they are taken up to eleven in CODE BLACK, as the show has cells getting killed a lot due to the body's unhealthy habits. As I never read the original manga due to it being an 18+ manga, I cannot tell any differences from it and the anime (which here in the States, is given a TV-14 rating), but the episodes do retain some of the stories from it, which deal with stuff like smoking, alcohol, and other problems an adult human body may be infected with (some of them I cannot name to keep this review clean). Also, because of the state the body is in, characters are less friendly to each other and even yell at each other as they are in a rush (even the cute little Platelets can be mean, as one scene in the first episode has one yelling at AA2153 to get out of the way, then apologizing after he lets them through, explaining everyone is on edge).