B Cell is a specialized lymphocyte within the adaptive immune system, tasked with combating antigens like bacteria and viruses. This character generates precisely calibrated protein antibodies designed to neutralize specific invading pathogens. Physically, he appears as an average-looking male cell with black messy hair and eyes, wearing a professional yet understated outfit: a black polo shirt, grey slacks, a matching vest, and a purple tie, reflecting his technical role.

B Cell exhibits a highly detail-oriented and methodological personality, committed to precision in antibody production for maximum effectiveness. He operates through humoral immunity, providing essential support rather than direct combat like phagocytic cells. His work involves close collaboration with Memory Cell, who supplies historical data on past antigen encounters to guide antibody development. While this partnership is crucial, Memory Cell's scatterbrained tendencies sometimes create coordination challenges. B Cell leverages this immune memory for rapid antibody deployment upon re-exposure to known threats, enabling faster and more efficient responses during secondary encounters. This function underpins acquired immunity and the biological basis for vaccination within the narrative.

As a white blood cell in the B lymphocyte lineage, his background includes documented responses to various antigen invasions throughout the series. His core abilities center on antigen recognition and the synthesis of diverse antibody variants tailored to different pathogens. B Cell also contributes to allergic reactions by producing antibodies against harmless substances based on inherited genetic data. His work demonstrates immunological memory principles, where initial antigen exposure creates blueprint antibodies stored for future use via Memory Cell's records. He functions alongside other lymphocytes such as Killer T Cells and NK Cells within the body's defensive network.