A demon hag (more like an Onibaba) who appears in the 8th episode. According to Satsuki's mom's 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 Yomi-Net to do the same scheme, in which Reo nearly becomes a victim. The only way to defeat him is to use an o-fuda and wish him to go back home. (Source: Wikipedia)