Junya Kanzaki

Nishimura Gosaku, an aspiring photographer who loves mountain scenery, meets a boy named Sada Ichiro one evening who asks to borrow train fare. For some reason, Ichiro follows Nishimura everywhere. When told to go home, Ichiro refuses, claiming he doesn't want to return because of his estranged parents. Reluctantly, Nishimura lets Ichiro stay the night. The next day, Nishimura takes photos of Ichiro by the Sumida River, and they part ways on good terms. Meanwhile, Ichiro's worried father, Shigeo and mother, Fujiko, desperately ask Ichiro's classmates and tutoring teachers for his whereabouts, but no one knows where he is. Suddenly, Shigeo receives a phone call demanding a ransom of 10 million yen.

Samon Kamiyama, a yoriki of the Minami-machi magistrate infiltrates the Denzū-machi prison disguised as Mushuku Sahēji. Samon is mistaken for a snitch and about to be beaten up when he was saved by the quick thinking of a ferryman Sanji. The infiltration is the plan of Samon and chief elder Abe Isenokami, who has asked Samon to obtain smuggling evidence against shipping whole retailers Kawachiya Senemon and his son Sennosuke.