Name (Number): U-4989 Affiliation: White Blood Cell (Neutrophil) Division Primary Mission: Eliminating foreign substances such as bacteria and viruses that have invaded the body. Characteristics and Personality Appearance: Dressed in the standard white uniform of the White Blood Cells. Compared to other neutrophils, he has slightly wavy hair and somewhat larger eyes. In comedic or deformed scenes, he is often drawn with bulging eyes. Personality: Extremely cheerful and a bit of a jokester, serving as the mood maker among his neutrophil colleagues. He has a free-spirited side, often depicted in comical situations like swimming in a washbasin or roasting marshmallows over a campfire. He is also sensitive and cares deeply for his comrades, showing concern for the protagonist U-1146's well-being and valuing their friendship. Mannerisms: He occasionally adds "-kero" to the end of his sentences. Relationships Best Friends Group: He is very close with the protagonist U-1146, as well as colleagues U-2048 and U-2626. In a photo distributed by a Dendritic Cell, the four of them were seen in a photo-booth style picture labeled "Best Friends Forever," leading fans to call them the "Zuttomo (BFF) Group." Abilities and Equipment Primary Weapon: Like other neutrophils, he uses a knife, but he also shows a creative side by improvising weapons, such as tying a knife to a pole to make a makeshift spear. Basic Abilities: Possesses standard neutrophil capabilities, including migration (moving through body tissues), receptors (bacteria detection radar), and phagocytosis (consuming and eliminating bacteria).

U-1146: The ace of the White Blood Cell Division. While ruthlessly serious during work, he is naturally very kind and helpful. He frequently assists Red Blood Cells. U-2048: Characterized by his spiked hair. Always calm, collected, and a cool professional. He serves as the group's anchor, quietly watching over the boisterous 4989. U-2626: Characterized by long bangs that cover both eyes. Quiet and reserved, he is a healing presence who gently supports his comrades. 2. Relationships Common: The four members, including 4989, are bound by a deep bond similar to being in the same graduating class, and are close enough to spend their time off together. 3. Abilities and Equipment Common Weapons: All are proficient with the standard-issue knife. Basic Abilities: All possess high combat skills as White Blood Cells, including "Migration" (passing through walls), "Receptors" (bacteria detection), and "Phagocytosis" (consuming bacteria).

U-2048: Characterized by his spiked hair. Always calm, collected, and a cool professional. He serves as the group's anchor, quietly watching over the boisterous 4989.

U-2626: Characterized by long bangs that cover both eyes. Quiet and reserved, he is a healing presence who gently supports his comrades.