|ANIME DEBUT||Episode 3|
|MANGA DEBUT||Chapter 2|
B Cell (Ｂ細胞 Bī Saibō?) is a minor character in Cells at Work!.
He is a white blood cell, specifically a B Cell (B Lymphocyte). He is tasked with producing antibodies as weapons to fight any antigens and foreign invaders, such as bacteria and viruses. He depends on Memory Cell to supply information so he can make antibodies that fit each specific antigen.
He appears to be a youth with brown spiky hair and gray eyes. He wears the B cell uniform and usually seen with his antibody gun.
B Cell is a cheeky cell that is very confident in his abilities, he likes to be praised and loathes being ignored.
Like other B Cells, he responds against threats using his antibodies.
- Overall Abilities: Although he is always delayed to an invasion as he requires time to prepare antibodies, but it is highly beneficial in terminating bacterium.
- Antibody Gun: His antibody gun is a weapon he made. The gun can secrete many types of antibodies to fight against antigen depending on its species. Later on B cell had upgraded the antibody gun, making it light so it "feels like air". 
- ↑ Cells at Work! Manga, Chapter 10