Babylon follows prosecutor Zen Seizaki after he is assigned to a case in Tokyo's newly formed Shiniki district, where a false-advertising complaint pulls him toward Japan Supiri, a pharmaceutical company accused of fabricating clinical research for a new drug. Working with his assistant officer Atsuhiko Fumio, Zen traces the investigation deeper into a widening scandal. The paper trail eventually points to Shin Inaba, an anesthesiologist connected to the case, and to a disturbing clue: a page stained with blood, hair, and skin, marked again and again with the letter "F".
As Babylon expands beyond a single fraud investigation, the story ties the Shiniki mayoral election to the district's creation and to a growing group of people whose interests and secrets overlap in increasingly dangerous ways. A mysterious woman appears to connect each new revelation, while the series turns its legal setup into a political thriller about corruption, manipulation, and the way power can warp medicine, public trust, and the lives of everyone caught in the middle.