Hakata Tonkotsu Ramens 4 (博多豚骨ラーメンズ 4) is the fourth light novel of the series. It was published on August 25, 2015.
A great cyber terrorist organization makes their landing in the city of Hakata. Aware of the organization plotting to assassinate skillful hackers, Enokida hurries in his investigation. Around the same time a client appears at the Banba Detective Office in search of Enokida. After encountering a familiar face and receiving a special request from him, Enokida has to confront the past he cut himself from once more. And with the organization hunting down Enokida, Xianming Lin and Zenji Banba are also caught up in the crossfire. 
|Prologue||Seasonal Opening Ceremony|