During the era of Tokugawa Ieyasu, one night a carver named Fujijiro was murdered. Immediately launching an investigation, Denhichi, accompanied by Otoshi and Take, toured the entertainment houses of Ryogoku. There, they discovered a connection between an acrobat and the incident. On their way home, Otoshi unexpectedly encountered an old friend, Inosuke, nervously buying a dagger. Inosuke, a clerk at the Kashimaya store, was in love with Oko, a secret lover of Bunzaemon. Amidst this, Seihei, the head clerk, was murdered by someone, and a dagger belonging to Inosuke was found at the scene, leading Gohei to suspect Inosuke as the culprit. However, Otoshi was hiding Inosuke. Driven by Otoshi's plea and a professional instinct that Inosuke wasn't the perpetrator, Denhichi desperately searched for the real culprit.