Hataraku Saibou Black

Inside a body worn down by smoking, alcohol, sleep deprivation, and constant stress, the cells work in conditions that offer them almost no relief. Rookie red blood cell AA2153 begins his job with enthusiasm, only to learn that delivering oxygen here is genuinely dangerous: blood vessels narrow, harmful substances spread, and new crises arrive before the previous ones are resolved. Beside him, white blood cell U-1196 fights invading pathogens without pause while workers across the body lose colleagues under a relentless workload. Every cell still tries to perform its duty, but the body's condition keeps deteriorating. Tasks that should be routine become exhausting battles for survival, and simply keeping their world functioning for one more day starts to feel like an achievement.