Gegege no Kitaro season 1 episode 48
Episode title: The Void of Despair and Darkness
Nearly twenty years into the 21st century, people have forgotten the existence of Yokai. When a number of unexplainable phenomena plague adults of the human world with confusion and chaos, thirteen-year-old Mana writes a letter to the Yokai Post in search of answers, only to be greeted by GeGeGe no Kitaro...
