Cells at Work! Wiki
 ROMANJI Kōsankyū
 SPECIES Eosinophil Cell
 AFFILIATION Eosinophil Division
 ANIME DEBUT Episode 4
 MANGA DEBUT Chapeter 5
 ENGLISH Kayli Mills

Eosinophil (好酸球 Kōsankyū?) is a minor character in Cells at Work!.

Eosinophil is a type of white blood cell, specifically an Eosinophil. Along with other eosinophils, she is tasked with defending the body from invading parasites and infections. Along with mast cells and basophils, eosinophils regulate allergies and asthma. She is also a type of Granulocyte.


Eosinophil appears to be a normal youth with blonde hair and gold eyes. Her hair is tied up in pigtails with white-colored hairbands. She wears the mostly-pink eosinophil uniform.


Eosinophil appears to be serious girl outside, as she rarely shows any emotion despite getting teased by other cells because of her weak abilities when fighting against bacteria. But when her specific situations arise, she stands and delivers with devastating efficiency. Covertly, she is actually a timid and reserved girl who gets easily flustered by compliments.


Raised in the bone marrow, she was taught to destroy foreign substances, especially parasites, upon sight.

  • Overall Abilities: As a white blood cell, she is capable of combat, although she is weaker against bacteria, viruses, and other common enemies than fellow fighters such as neutrophils and killer T cells.
  • Phagocytosis: Compared to other white blood cells, her phagocytosis is rather weak. White blood cells can analyze an unknown foreign cell by eating them, which will help them identify its species, or consume them as food.
  • Sasumata Proficiency: Eosinophil fights primarily using her sasumata, a pole weapon rarely found outside of Japan. As a polearm, it is likely used with the intention of combat against large parasites, rather than similarly-sized bacteria and viruses.


  • As mentioned in the manga, eosinophils compose a small percent of all white blood cells, only about 1-3%.[1][2]
  • Eosinophil's weapon, the sasumata, was used by samurai and their retainers in feudal Japan. Now, the sasumata is commonly used in schools as a non-lethal weapon to defend against classroom invasions.[3]
  • Her twin pigtails (and possibly the two-pronged nature of her sasumata) may be based on the distinct bi-lobed shape of eosinophil nuclei.
  • Her uniform's pink color is a reference to eosinophils being stained pink when washed with the dye Eosin.


  1. Uhm TG, Kim BS, Chung IY (March 2012). "Eosinophil development, regulation of eosinophil-specific genes, and role of eosinophils in the pathogenesis of asthma". Allergy, Asthma & Immunology Research. 4 (2): 68–79.
  2. Young B, Lowe jo, Stevens A, Heath JW (2006). Wheater's Functional Histology (5th ed.). Elsevier Limited. ISBN 978-0-443-06850-8.
  3. Mainichi Shinbun 2004.