One day, Hinako, a high school student, finds her path to school transformed into the Sanzu River, where she meets a strange-looking man named Issa. Will she be able to get through the mysterious devices of the mysterious mansion and return safely to her family?

One day, Hinako, a high school student, finds her path to school transformed into the Sanzu River, where she meets a strange-looking man named Issa. Will she be able to get through the mysterious devices of the mysterious mansion and return safely to her family?