A demon hag more like an Onibaba who appears in the 8th episode. According to Satsuki039s mom039s diary he used to take lost people to the boats of the Sanzu River and then forced them to enter in a boat to cross the river in other words to the underworld. However it seemed his activities stopped with the installment of lights in the city. He now uses a legendary Internet site called YomiNet to do the same scheme in which Reo nearly becomes a victim. The only way to defeat him is to use an ofuda and wish him to go back home. Source: Wikipedia