In the crime-ridden underworld of Fukuoka's Hakata ward, where elite assassins and detectives converge, a renowned figure known as the Niwaka Samurai reigns supreme as an 'assassin of assassins.' Amidst this chaos, Banba Zenji, a laid-back private eye who juggles solving cases for his police pal and playing baseball, finds himself at the center of a storm. Targeted by a formidable criminal organization and crossing paths with the enigmatic cross-dresser Lin Xianming, Banba's peaceful existence in Hakata is about to take a drastic turn.