|Senior Red Blood Cell AA5100|
|SPECIES||Red Blood Cell|
|ANIME DEBUT||Episode 1|
|MANGA DEBUT||Chapter 2|
AA5100, Senior Red Blood Cell (先輩赤血球 Senpai Sekkekkyū?) is a minor character in Cells at Work!
AA5100 has long brown hair, eyes, fair skin, and an oval shaped head. She wears a standard red blood cell uniform.
AA5100 is kind as well as informative and supportive toward the juniors she's responsible for.
She is an older red blood cell with decent working experience in the blood vessels. She sometimes guides and teaches AE3803 how to do her job when she is confused or lost.
As a red blood cell, she is a worker that is unable to protect herself. Therefore her job is to only transport goods.
- Overall Abilities: Despite having no abilities to defend herself, she is capable of transporting goods into all corners of the body with high acceleration. She's even adept at getting through incredibly tight spaces, albeit with considerable difficulty.
- Reversible Jacket: All red blood cells wear a reversible jacket that helps them indicate their speed when moving around in either veins or arteries. The jacket has extendable sleeves and zips up for colder weather.