Divine Incursions, Vol. 2 (manga)

Giants at the bottom of a dam, gods of retribution...strange and Incomprehensible phenomena are accelerating! Not only his boss but also his brother-in-law, Rokuhara is someone Katagishi of the Divine Incursion Special Investigations Department would rather not deal with. But he is going to have to, because he's been assigned to investigate a certain dam with Rokuhara. What link will they find between the dark giant standing at the bottom of the dam and a monster luring in people through voice mimicry...