Dogen and Okane forges Oasa's letter and visits the master of Iseya, and blackmails him by picking a quarrel for sleeping with Oasa, but they retreat in disappointment when Matsuzo who dashes into the scene drops a hint of the murder at Ochanomizu with evidence of a tobacco pouch that Dogen had dropped and lost.
おあさの贋手紙をこしらえた道玄とお兼は、伊勢屋の主人に面会しおあさが同衾したと因縁を吹っかけ強請りを働くが、駆けつけた松蔵に、道玄の落とした煙草入れを証拠にお茶の水の殺人を仄めかされ、二人はすごすごと退散する。