Hakata Tonkotsu Ramens unfolds in Fukuoka, a city that seems ordinary at first glance but conceals a dense underworld of hitmen, detectives, informants, and people who make their living from revenge. At the center of that world is Zenji Banba, a laidback yet sharp-eyed detective who spends his days digging into the operations of rival assassination companies. Moving through the same shadows is Xianming Lin, a crossdressing male hitman employed by one of those groups, who is increasingly fed up with the lack of work and the miserable pay that comes with it.
The trouble begins when Lin’s current target dies by suicide before he can complete the job, and his company refuses to pay him even the promised half. Angry and looking for a new assignment, Lin is instead ordered to eliminate Banba, whom his employers suspect of interfering with their business. But when Banba shows up at Lin’s home and finds the hitman waiting there, Lin makes a surprising choice: he refuses to kill him and offers a different path, asking the detective to join him and form a team instead.
From that uneasy alliance, Hakata Tonkotsu Ramens dives deeper into Fukuoka’s criminal ecosystem, where grudges, contracts, and shifting loyalties can alter the balance of power in an instant.