纽约。有着非凡的姿容，和卓越战斗力的少年·亚修。统领街头暴力团的他听到了，被手下所杀的男人在临死之际说出的“BANANA FISH”的神秘话语。与此同时，他与作为摄影师的助手来取材的日本少年·奥村英二相遇。两人决定一同追寻“BANANA FISH”之谜——

Although the city of Fukuoka might look relatively peaceful at first glance, in actuality it houses a thriving mixture of dangerous individuals such as killers, detectives, and professional revenge seekers right beneath its surface. Among their number is Zenji Banba, a laidback and observant detective who is investigating the work of other hitmen companies in the area. However, Banba might not be the only one with a bone to pick with these organizations, as Xianming Ling, a crossdressing male hitman in the employ of one such company begins getting fed up with his lack of jobs and pay.

One day, after Ling's current target commits suicide before the hitman could reach him, his company refuses to pay him even half the amount they were originally supposed to for the assassination. Frustrated, Ling requests another mission and is offered the job of taking out Banba, whom his organization believes has been interfering with their business. However, when Banba arrives at his home and finds the hitman inside, Ling surprisingly doesn't even attempt to kill him. Instead, he offers the detective another option: to join him and form a team. With the offer on the table, exactly how will Banba respond, and just what plans does Ling have in store for the underground world of Fukuoka?

In the shadows of this world, ninjas fight for control of an ancient technique which holds untold strength. This coveted power dwells within apathetic Miharu, a fact the guy really couldn't care less about - until the rival clans bring their battle to him. Now, he must choose a side if he hopes to survive - but when conflict is waged in secret, friend and foe prove difficult to tell apart.