Hyaku Monogatari (百物語; Literally meaning "Hundred Tales") was a means by which the Hyaku Monogatari Clan increased their influence through creating new yōkai tales. It began as a game played by rogue samurai at night. At a gathering of 100 samurai, they took turns telling ghost stories and each blew a candle out afterward. It was believed that after the final candle was extinguished, a yōkai would appear. It was often used by the wealthy as a means of entertainment, but among them, a powerful demon named Sanmoto Gorōzaemon began gathering all of the yōkai created through this process and made them his underlings. This was evidently the basis for the Hyaku Monogatari Clan.
Known as Hyakumonogatari Kaidenkai (百物語怪談会; Literally meaning "A Gathering of One Hundred Supernatural Tales"), it was a popular parlor game during Japan's Edo era. In a room at night, 100 candles were lit and those present took turns telling ghost stories. After each story's completion, a candle was blown out. After the final candle was extinguished, supposedly a supernatural being would be summoned forth.
The game's origins are unknown, but it is believed to have been first played by samurai as a test of courage. The popularity of the practice, combined with new printing technology, created a boom in the publication of books centered around ghost stories.